Process for the production of metal oxides or citric acid

ABSTRACT

The present application pertains to methods for making metal oxides and/or citric acid and/or capturing carbon dioxide. In one embodiment, the application pertains to a process for producing calcium oxide, magnesium oxide, or both from a material comprising calcium and magnesium. The process may include reacting a material comprising calcium carbonate and magnesium carbonate. Separating, concentrating, and calcining may lead to the production of oxides such as calcium oxide or magnesium oxide. In other embodiments the application pertains to methods for producing an alkaline-earth oxide and a carboxylic acid from an alkaline earth cation-carboxylic acid anion salt. Such processes may include, for example, reacting an alkaline-earth cation-carboxylic acid anion salt with aqueous sulfur dioxide to produce aqueous alkaline-earth sulfite or bisulfite and an aqueous carboxylic acid solution. Other useful steps may include desorbing, separating, and/or calcining.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part application of pending U.S. Ser. No. 17/590,483 filed Feb. 1, 2022 which application is a continuation of U.S. Ser. No. 17/243,714 filed Apr. 29, 2021 which application is U.S. Pat. No. 11,236,033. U.S. Ser. No. 17/243,714 is a continuation in part of U.S. application Ser. No. 16/944,850 filed Jul. 31, 2020 which application claims priority to U.S. provisional application No. 62/895,557 filed Sep. 4, 2019 and U.S. provisional application No. 63/042,397 filed Jun. 22, 2020 and U.S. provisional application No. 62/890,254 filed Aug. 22, 2019. All applications are incorporated by reference in their entirety.

This application is also related to U.S. Ser. No. 17/243,704 filed Apr. 29, 2021 which is now U.S. Pat. No. 11,174,169.

BACKGROUND AND SUMMARY

CaO is currently produced by heating CaCO3 or limestone to decompose it into CaO and CO2 in a process called calcining. Calcining is energy intensive and CO2 emission intensive. The process of calcining produces CO2 in the form of flue gas. A similar process is currently used in the production of cement, such as portant cement. For CO2 to be useful from calcining, the CO2 must be separated from the flue gas by a post-combustion CO2 capture system, which requires very high capital and operating costs, which generally exceed the value of said CO2. Alternatively, a calciner may be powered by fuel combusted in pure oxygen (oxy-combustion) from an air separation unit. Oxy-combustion has high capital and operating costs due to the required air separation unit and the significantly higher operating temperature required for decomposing CaCO3 in a pure environment CO2.

The present invention may react SO2 (gas or liquid or aqueous solution or non-aqueous solution or supercritical or solid or a combination thereof) with CaCO3, which may result in the formation of CaSO3 and CO2. The resulting CO2 may undergo further purification to remove, for example, at least a portion of SO2 or any other gases present from the CO2. CO2 may be sold or used for one or more applications of high pressure and/or purity CO2. CaSO3 may be thermally decomposed into CaO and SO2. The thermal decomposition of CaSO3 may involve an oxygen free or ultra-low oxygen environment. The thermal decomposition of CaSO3 may be conducted in the presence of a combustion flue gas or a carrier gas or a combination thereof. SO2 may be separated and may be recovered or regenerated for re-use internally. Advantageously, SO2 possesses a significantly greater solubility in water and/or other physical solvents than CO2, which may enable the use of physical solvents to separate SO2 and/or may enable the use of a SO2 wash solution to react SO2 with CaCO3. CaO may be sold or used for one or more applications of CaO. The process may be batch, semi-batch, semi-continuous, continuous, or a combination thereof.

The present invention may pertain to systems, methods, and processes for producing calcium oxide or magnesium oxide or lime or sodium oxide or potassium oxide other oxide salt from a carbonate salt while intrinsically generating relatively high partial pressure CO2 and/or relatively high purity CO2. The present invention may pertain to systems, methods, and processes for producing cement from a carbonate salt while intrinsically generating relatively high partial pressure CO2 and/or relatively high purity CO2. Calcium and magnesium salts may be provided as example salts, although other cations capable of forming carbonate, bicarbonate, or oxide salts or ionic compounds are applicable to the present invention. Some embodiments may involve reacting a regenerable acid or regenerable acid gas with calcium carbonate and/or magnesium carbonate to produce an intermediate comprising calcium-acid gas and/or magnesium-acid gas and an output comprising captured CO2. Said calcium-acid gas and/or magnesium-acid gas intermediate may be converted into an intermediate comprising regenerable acid gas and an output comprising calcium oxide or magnesium oxide or cement. Some embodiments may employ a regenerable acid gas which may be regenerated using, for example, including, but not limited to, heat, electricity, light, condensation, absorption, gas-forming reaction, gas-forming decomposition, electrodialysis, or a combination thereof.

The present invention may involve employing acid gases with regeneration or recovery properties which may be more desirable or advantageous than, for example, CO2. For example, sulfur dioxide (SO2) is significantly more soluble in water than CO2 at the same vapor pressure and temperature, and/or sulfurous acid (aqueous sulfur dioxide) displaces CO2 in carbonate salts to form sulfite or bisulfite or metabisulfite salts. Sulfite or bisulfite or metabisulfite salts may possess decomposition temperatures and enthalpies of decomposition similar to carbonate salts. Said more desirable or advantageous properties may include, but are not limited to, solubility in water, solubility in one or more solvents or liquids, enthalpy of desorption, enthalpy of absorption, enthalpy of reaction, or a combination thereof. Some embodiments may involve systems and methods for preventing oxidation or degradation or contamination of the acid gas, or preventing oxidation or degradation or contamination of the calcium oxide, or preventing degradation or contamination of the carbon dioxide, or preventing degradation or contamination of a physical solvent or a combination thereof.

The present invention also may comprise a process for producing calcium oxide and/or magnesium oxide from a material comprising calcium and/or magnesium. The present invention may comprise a process for calcium oxide and/or magnesium oxide and/or captured carbon dioxide from a material comprising calcium carbonate and/or magnesium carbonate. The present invention may include processes for separating at least a portion of magnesium from a material comprising calcium and magnesium. The present invention may include processes for separating at least a portion of calcium from a material comprising calcium and magnesium. The present invention may include processes for producing high purity carbon dioxide, or high partial pressure carbon dioxide, or both. The present invention may include processes forming an aqueous magnesium sulfite solution. The present invention may include processes for producing magnesium sulfite solid from an aqueous solution comprising magnesium sulfite. The present invention may include processes for separating impurities from a solution comprising magnesium sulfite. The present invention may include processes for drying or dehydrating magnesium sulfite solid, or calcium sulfite solid, or both. The present invention may include low energy, or low cost, or low CAPEX, or low OPEX, or a combination thereof processes for drying or dehydrating magnesium sulfite solid, or calcium sulfite solid, or both.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows an embodiment of a process for continuous production of CaO from CaCO3 or limestone or other typical CaO feedstocks.

FIG. 2 shows an embodiment comprising a process for producing CaO from CaSO3.

FIG. 3A shows an embodiment comprising a process for producing CaSO3 and CO2 from CaCO3 and SO2.

FIG. 3B shows an embodiment comprising a process for producing CaSO3 and CO2 from CaCO3 and SO2 with each reactor undergoing a different stage than in FIG. 3A.

FIG. 3C shows an embodiment comprising a process for producing CaSO3 and CO2 from CaCO3 and SO2 with each reactor undergoing a different stage than in FIG. 3A.

FIG. 4: A process for producing calcium oxide and magnesium oxide from a material comprising calcium and magnesium which may involve a process for concentrating and/or precipitating magnesium sulfite, and/or may involve calcining wet calcium sulfite and/or wet magnesium sulfite, and/or may involve producing captured carbon dioxide.

FIG. 5: A process for producing calcium oxide and magnesium oxide from a material comprising calcium and magnesium which may involve a process for drying wet calcium sulfite and/or wet magnesium sulfite before calcining calcium sulfite and/or magnesium sulfite and/or may involve absorbing sulfur dioxide gas in a permeate comprising water produced from a membrane-based process.

FIG. 6: A process for producing calcium oxide and magnesium oxide from a material comprising calcium and magnesium which may involve recirculating residual aqueous magnesium sulfite.

FIG. 7: A process for producing calcium oxide and magnesium oxide from a material comprising calcium and magnesium which may involve transferring residual aqueous magnesium sulfite to a sulfur dioxide absorption process.

FIG. 8: A process for producing calcium oxide and magnesium oxide from a material comprising calcium and magnesium which may involve a process for removing at least a portion of non-magnesium sulfite impurities from a solution comprising aqueous magnesium sulfite.

FIG. 9: A process for producing calcium oxide and magnesium oxide from a material comprising calcium and magnesium which may involve producing calcium oxide and/or magnesium oxide without a captured CO2 co-product during the reaction of the material comprising calcium and/or magnesium with aqueous sulfur dioxide.

FIG. 10: A process for producing calcium oxide and magnesium oxide from a material comprising calcium and magnesium including makeup sulfur dioxide.

FIG. 11: A figure with numerical labels showing a process for producing calcium oxide and magnesium oxide from a material comprising calcium and magnesium.

FIG. 12: A figure showing a process for producing citric acid with regeneration of calcium oxide.

DETAILED DESCRIPTION OF THE INVENTION Example Definitions

-   -   Regenerable Acid Gas or Regenerable Acid: A regenerable acid may         comprise an acidic chemical which can form a salt and is capable         of being regenerated from said salt into its original acidic         chemical form. For example, a regenerable acid may comprise an         acid which can be reacted to form a salt and can be regenerated         from said salt by, for example, thermal decomposition of said         salt, which may involve, for example, a gas forming         decomposition. For example, a regenerable acid may comprise an         acid which can be reacted to form a salt and can be regenerated         from said salt by, for example, electrochemical means, which may         include, but is not limited to, electrodialysis. A regenerable         acid gas may be an acid which is generally at a gas phase when         said acid is at an isolated state under certain conditions.         Regenerable acid and regenerable acid gas may be used         interchangeably. Example regenerable acid gases or acids may         include, but are not limited to, one or more or a combination of         the following: sulfur dioxide, nitrogen dioxide, nitrogen         monoxide, hydrogen sulfide, silicic acids, or orthosilicic acid.         Example regenerable cation-acid gas salts may include, but are         not limited to, one or more or a combination of the following:         sulfites, bisulfites, metabisulfites, nitrites, carbonates,         silicates, calcium sulfite, magnesium sulfite, calcium         bisulfite, magnesium bisulfite, calcium nitrite, magnesium         nitrite, calcium nitrate, magnesium nitrate, calcium carbonate,         magnesium carbonate, calcium bicarbonate, magnesium bicarbonate,         calcium silicates, magnesium silicates, sodium sulfite, sodium         bisulfite, sodium metabisulfite, sodium nitrate, sodium nitrite,         sodium carbonate, sodium bicarbonate, sodium sequicarbonate,         sodium silicates, alkaline-earth metal cation salts,         alkaline-earth metal cation salts with anions described herein,         alkali metal cation salts, alkali metal cation salts with anions         described herein.     -   CaO: CaO may comprise calcium oxide. CaO may also be provided as         an example oxide salt and may represent other oxide salts, which         may include, but are not limited to, oxide salts of calcium,         magnesium, sodium, potassium, lithium, ammonia, iron, zinc,         aluminum, copper, or a combination thereof. CaO may also         represent cement, which may include, but is not limited to, one         or more or a combination of the following: hydraulic cement,         non-hydraulic cement, or Portland cement. CaO may comprise a         CO2-lean alkaline-earth.     -   CaCO3: CaCO3 may comprise calcium carbonate. CaCO3 may also be         provided as an example carbon dioxide salt and may represent         other carbon dioxide salts, which may include, but are not         limited to, carbon dioxide salts of calcium, magnesium, sodium,         potassium, lithium, ammonia, amine, iron, zinc, copper, or a         combination thereof. CaCO3 may comprise limestone. CaCO3 may         comprise a CO2-rich alkaline-earth.     -   CaSO3: CaSO3 may comprise calcium sulfite. CaSO3 may also be         provided as an example regenerable acid gas salt and may         represent other regenerable acid gas salts, which may include,         but are not limited to, carbon dioxide salts of calcium,         magnesium, sodium, potassium, lithium, ammonia, amine, iron,         zinc, copper, or a combination thereof.     -   Carbon Dioxide Salt: A salt originating from or containing or         comprising carbon dioxide. A carbon dioxide salt may include,         but is not limited to, carbonates, bicarbonates, carbamates,         sesquicarbonates, or a combination thereof.     -   Intermediate: An intermediate may comprise a reagent which is         internally regenerated. An intermediate may comprise a reagent         which is at least a portion regenerated inside the process. An         intermediate may comprise a reagent which is not a primary input         or output of the process. An intermediate may comprise a         catalyst. Example intermediates may include, but are not limited         to, one or more or a combination of the following: a regenerable         acid gas or an absorption solution.     -   Combustion Gases or Post-Combustion Gases: Combustion gases or         post-combustion gases may comprise gases or a gas mixture         forming as a result of the combustion of one or more fuels.     -   Fuel-Rich Mixture: A mixture of fuel and an oxidant which         possess a higher ratio of fuel to oxidant relative to a         fuel-lean mixture. For example, mixture of fuel and an oxidant         which possesses a ratio of fuel to oxidant which is close to, or         equal to, or greater than the stoichiometric ratio of fuel to         oxidant for complete combustion. Oxidant may comprise diatomic         oxygen, air, or other oxidant.     -   Fuel-Lean Mixture: A mixture of fuel and an oxidant which         possess a lower ratio of fuel to oxidant relative to a fuel-lean         mixture. For example, mixture of fuel and an oxidant which         possesses a ratio of fuel to oxidant which is close to, or equal         to, or less than the stoichiometric ratio of fuel to oxidant for         complete combustion. Oxidant may comprise diatomic oxygen, air,         or other oxidant.     -   Low Oxygen Environment or Low Oxygen Atmosphere or Low Diatomic         Oxygen Environment or Low Diatomic Oxygen: May comprise one or         more or a combination of the following:         -   Comprises a diatomic oxygen concentration less than 20 vol             %, or less than 15 vol %, or less than 10 vol %, or less             than 9 vol %, or less than 8 vol %, or less than 7 vol %, or             less than 6 vol %, or less than 5 vol %, or less than 4 vol             %, or less than 3 vol %, or less than 2 vol %, or less than             1 vol %, or less than 0.5 vol %, or less than 0.25 vol %, or             less than 0.1 vol %, or less than 0.05 vol %, or less than             0.01 vol %, or less than 0.005 vol %, or less than 0.001 vol             %, or less than 0.0001 vol %.         -   A volume-percent concentration of gaseous diatomic oxygen             less than average concentration of oxygen in air or a             diatomic oxygen concentration of less than or equal to 21             vol %     -   Low Dissolved Oxygen Concentration or Low Dissolved Diatomic         Oxygen Concentration:         -   A dissolved oxygen concentration less than 10,000 PPM, or             less than 5,000 PPM, or less than 1,000 PPM, or less than             500 PPM, or less than 250 PPM, or less than 100 PPM, or less             than 50 PPM, or less than 25 PPM, or less than 10 PPM, or             less than 7.5 PPM, or less than 5 PPM, or less than 2.5 PPM,             or less than 1 PPM.         -   Less than the saturated solubility of dissolved oxygen at             the vapor pressure of diatomic oxygen in the headspace above             a solution.     -   Carbonaceous Fuel: A fuel comprising carbon. A carbonaceous fuel         may comprise a hydrocarbon, a carbon containing compound,         elemental carbon, a mixture with carbon, or a combination         thereof.     -   Sulfurous Fuel: A fuel comprising sulfur. A sulfurous fuel may         include, but is not limited to, sulfur, elemental sulfur,         hydrogen sulfide, hydrocarbons comprising sulfur, sulfur         dioxide, sulfur trioxide, sulfides, salts comprising sulfur,         mercaptans, organosulfur compounds, nitrogenous sulfur compound,         ammonium sulfate, ammonium sulfite, ammonium sulfide, or a         combination thereof.     -   Nitrogenous Fuel: A fuel comprising nitrogen. A nitrogenous fuel         may include, but is not limited to, ammonia, amine, ammonia         salts, ammonium salts, ammonium nitrate, ammonium nitrite,         ammonium sulfite, ammonium sulfide, ammonium carbonate, ammonium         carbamate, urea, ammonia derivatives, organic nitrogen         compounds, hydrocarbons comprising nitrogen, or a combination         thereof.     -   Hydrogen Fuel: A fuel comprising hydrogen. Hydrogen fuel may         comprise diatomic hydrogen or derivatives of hydrogen.     -   Other Cement Feedstocks: Other cement feedstocks may comprise         input materials for the production of cement other than calcium         carbonate. For example, other cement feedstocks may include, but         are not limited to, one or more or a combination of the         following: clay, or silicon dioxide, or aluminum oxide, or iron         oxide, or iron carbonate, or magnesium carbonate, or magnesium         oxide, or silicates, or silicon oxides, or aluminates, or shale,         or sand, or fly ash, or ash, or slag, or sulfur oxides.     -   Solid Material Undergoing Calcination: May comprise solid         materials undergoing thermal decomposition and/or calcination.         May comprise solid materials in a calciner. May comprise solid         materials entering or exiting a calciner.     -   Calcining Products: Calcining products may comprise outputs of a         calcination process. Calcining Products may refer to solid phase         products exiting a calcination process, which may include, but         are not limited to, alkaline-earth oxides, alkali oxides,         calcium oxide, magnesium oxide, cement, or a combination         thereof. Calcining products may refer to gaseous phase products         exiting a calcination process, which may include, but are not         limited to, sulfur dioxide, regenerable acid gas, carbon         dioxide, or a combination thereof.     -   Thermal Decomposition: May comprise calcination reactions. May         comprise an endothermic or temperature driven gas forming         reaction. May comprise other calcination reactions. Other         calcination reactions may include, but are not limited to, the         formation of calcium silicates and/or calcium aluminates and/or         sulfur based compounds.     -   First Combustion Step:         -   A first combustion step may comprise the combustion of a             fuel in a gas or oxidant or both in at least a portion of a             fresh gas or a gas mixture which previously did not undergo             combustion.         -   May comprise combustion which decreases the gas phase             diatomic oxygen concentration from 10-100 vol % to less than             20 vol %, or less than 19 vol %, or less than 18 vol %, or             less than 17 vol %, or less than 16 vol %, or less than 15             vol %, or less than 14 vol %, or less than 13 vol %, or less             than 12 vol %, or less than 11 vol %, or less than 10 vol %,             or less than 9 vol %, or less than 8 vol %, or less than 7             vol %, or less than 6 vol %, or less than 5 vol %, or less             than 4 vol %, or less than 3 vol %, or less than 2 vol %, or             less than 1 vol %. Vol % of diatomic oxygen means the             volume-percent concentration of diatomic oxygen in the gas             phase.     -   Second Combustion Step:         -   A second combustion step may comprise the combustion of a             fuel in a gas or oxidant or both in a gas or gas mixture             which previously underwent combustion.         -   May comprise combustion which decreases diatomic oxygen             concentration from 0.1-20 vol % to less than 20 vol %, or             less than 15 vol %, or less than 10 vol %, or less than 9             vol %, or less than 8 vol %, or less than 7 vol %, or less             than 6 vol %, or less than 5 vol %, or less than 4 vol %, or             less than 3 vol %, or less than 2 vol %, or less than 1 vol             %, or less than 0.5 vol %, or less than 0.25 vol %, or less             than 0.1 vol %, or less than 0.05 vol %, or less than 0.01             vol %, or less than 0.005 vol %, or less than 0.001 vol %,             or less than 0.0001 vol %.     -   Diatomic Oxygen-Rich Gas: A gas or gas mixture comprising a         higher partial pressure or concentration or both of diatomic         oxygen relative to a Diatomic Oxygen-Lean Gas. May comprise at         least a portion of a gas or gas mixture which previously did not         undergo combustion.     -   Diatomic Oxygen-Lean Gas: A gas or gas mixture comprising a         higher partial pressure or concentration or both of diatomic         oxygen relative to a Diatomic Oxygen-Ultra-Lean Gas. May         comprise at least a portion of a gas or gas mixture which         previously underwent combustion in a first combustion step.     -   Diatomic Oxygen-Ultra-Lean Gas: A gas or gas mixture comprising         a lower partial pressure or concentration or both of diatomic         oxygen relative to a Diatomic Oxygen-Lean Gas. May comprise at         least a portion of a gas or gas mixture which underwent         combustion in a second combustion step.     -   Combustion Step: A combustion step may comprise the combustion         of a fuel. A combustion step may comprise the combustion of a         fuel which results in a decrease in the partial pressure and/or         concentration of diatomic oxygen in a gas stream. A combustion         step may comprise the combustion of a fuel which results in the         increase in temperature of a gas stream or is exothermic. A         combustion step may comprise the combustion of a fuel until the         fuel ceases to combust.     -   Carbon Dioxide Generation Step: A carbon dioxide generation step         may comprise a reaction between a carbon dioxide salt and a         regenerable acid gas, which results in the formation of carbon         dioxide. Said formed carbon dioxide may be at a gaseous state.     -   Calcining Step: A calcining step may comprise a step involving         heat input or thermal decomposition or an endothermic gas         forming reaction or a temperature driven gas forming reaction or         a combination thereof.     -   Acid Gas Recovery Step: An acid gas recovery step may comprise         absorbing, separating, or capturing a regenerable acid gas.     -   Alkali: An alkali may comprise reagents comprising elements in         the alkali metal group in the periodic table.     -   Alkaline-Earth: An alkaline-earth may comprise reagents         comprising elements in the alkaline-earth metal group in the         periodic table.     -   High Purity of Carbon Dioxide: A volume-percent (vol %)         concentration of carbon dioxide greater than or equal to 30 vol         %, or 40 vol %, or 50 vol %, or 60 vol %, or 70 vol %, or 80 vol         %, or 90 vol %, or 95 vol %, or 99 vol %, or 100 vol %.     -   High Pressure: A partial pressure greater than or equal to 0.1         atm, or 0.5 atm, or 1 atm, or 1.5 atm, 2 atm, or 3 atm, or 4         atm, or 5 atm, or 6 atm, or 7 atm, or 8 atm, or 9 atm, or 10         atm, or 15 atm, or 20 atm.     -   Low Concentration of Water Vapor:         -   A water vapor pressure less than or equal to 1 atm, or 0.75             atm, or 0.5 atm, or 0.25 atm, or 0.175 atm, or 0.1 atm, or             0.09 atm, or 0.08 atm, or 0.07 atm, or 0.06 atm, or 0.05             atm, or 0.04 atm, or 0.03 atm, or 0.02 atm, or 0.01 atm, or             0.005 atm.         -   A water vapor vol % concentration less than or equal to 50             vol %, or 25 vol %, or 15 vol %, or 10 vol %, or 9 vol %, or             8 vol %, or 7 vol %, or 6 vol %, or 5 vol %, or 4 vol %, or             3 vol %, or 2 vol %, or 1 vol %.     -   Mild Temperature: A temperature less than or equal to 150° C.,         or 100° C., or 90° C., or 80° C., or 70° C., or 60° C., or 50°         C., or 40° C., or 35° C. A temperature greater than or equal to         −50° C., or −40° C., or −30° C., or −20° C., or −10° C., or 0°         C.     -   CO2-Rich Alkaline-Earth Solid: An alkaline earth compound with a         greater molar ratio of CO2 to alkaline-earth than CO2-Lean         Alkaline-Earth Solid. May comprise calcium carbonate or         magnesium carbonate or a combination thereof.     -   CO2-Lean Alkaline-Earth Solid: An alkaline earth compound with a         lower molar ratio of CO2 to alkaline-earth than CO2-Lean         Alkaline-Earth Solid. May comprise calcium oxide or magnesium         oxide or cement or a silicate or a combination thereof.     -   Physical Absorbent or Physical Solvent or Solvent: A liquid or         surface or a combination thereof wherein regenerable acid gas is         soluble. A physical absorbent may comprise a non-aqueous         solution. A physical absorbent may comprise water. A physical         absorbent may comprise a mixture of a non-water reagent with         water. A physical absorbent may comprise an aqueous solution.     -   Physical Absorbent Wash or Physical Solvent Wash or Solvent         Wash: An absorption column or wash or contactor or scrubber or a         gas-liquid contactor which employs physical absorbent as an         absorption solution.     -   Middle Concentration: A concentration greater than a lean         concentration and less than a rich concentration.         Example Chemistry

Example Summary of Inputs and Outputs for the Present Invention Inputs Outputs CaCO₃ and/or Other CaO and/or Cement Cement Feedstocks Fuel Captured CO₂ (Carbonaceous Fuel and/or Sulfurous Fuel and/or Hydrogen Fuel and/or Nitrogenous Fuel) Sulfurous Salt Waste-Product or Useful Byproduct

Please note—the Sulfurous Fuel and Sulfurous Salt Waste-Product or Useful Byproduct may comprise significantly smaller mass or amounts than other inputs and outputs.

Reaction 1: Conversion of CaCO3 and SO2 or SO2 Solution into CaSO3 and Captured CO2 CaCO₃(s)+SO₂(rich-aq)⇒CaSO₃(s)+SO₂(lean-aq)+CO₂(g) ΔH=−24.67 kj/mol at 25° C.

-   -   Description: The present reaction may involve reacting a carbon         dioxide containing salt or carbonate salt, such as calcium         carbonate, with a regenerable acid gas, such as sulfur dioxide,         to form pressurized or high concentration or nearly pure CO2 and         a regenerable acid gas salt, such as calcium sulfite. If         desired, the present reaction may be conducted under mild         temperature conditions, which may include, but are not limited         to, room temperature, 0-100° C., or less than 200° C., or less         than 190° C., or less than 180° C., or less than 170° C., or         less than 160° C., or less than 150° C., less than 140° C., less         than 130° C., or less than 120° C., less than 110° C., or less         than 100° C., or less than 90° C., or less than 80° C., or less         than 70° C., or less than 60° C., or less than 50° C., or less         than 40° C., or less than 30° C. Alternatively, or additionally,         it may be desirable to conduct the present step at relatively         colder temperatures, to, for example, minimize the vapor         pressure or concentration of SO2 in the headspace or gas phase.         Relatively colder temperatures may include, but are not limited         to, less than 50° C., or less than 45° C., or less than 40° C.,         or less than 35° C., or less than 30° C., or less than 25° C.,         less than 20° C., less than 15° C., or less than 10° C., or less         than 5° C. The CO2 generated may comprise substantially lower         concentrations of water vapor and/or other contaminants relative         to desorbed carbon dioxide in some post-combustion CO2 capture         systems, which may enable less or lower cost post-treatment         and/or compression. The CO2 generated may be present at         relatively high pressures, which may enable lower compression         costs and/or lower compression energy demand if subsequent         compression is desired. It may be desirable for the present         reaction to be conducted in a low diatomic oxygen or diatomic         oxygen free environment to, for example, prevent the formation         of more permanent sulfur oxides, such as sulfates and/or sulfur         trioxide. The present reaction may occur at a yield of 100% or         may occur at a yield less than 100%. If the yield of the present         reaction is less than 100%, a portion of calcium carbonate may         be present in the solid reaction product. The sulfur dioxide may         be dissolved in water. The sulfur dioxide may be dissolved in a         solution comprising a physical absorbent. Said physical         absorbent may comprise a one or more or a combination of         reagents in which sulfur dioxide and/or other acid gases is         soluble.     -   Conditions: It may be desirable to mix the input reagents under         standard conditions, which may include, but are not limited to,         room temperature pressure conditions. Alternatively, or         additionally, reagents may be mixed under high pressure         conditions to enable a higher partial pressure of CO2 during         desorption and/or a lower vol % concentration of water vapor         and/or SO2 relative to CO2 in the reactor headspace or         atmosphere. It may be desirable to conduct the present reaction         under a pure or nearly pure or high concentration CO2 atmosphere         to, for example, enable the process to generate high quality or         high concentration or high purity or a combination thereof         captured CO2 and/or to minimize the need for additional         treatment or compression during or after CO2 generation. Note         that during the present reaction, temperatures and pressures may         increase or decrease or a combination thereof. Reaction 1 may be         exothermic and may be a gas forming reaction—temperatures and/or         pressures may increase during Reaction 1. It may be desirable to         facilitate an increase in temperatures and/or pressures, or it         may be desirable to relieve an increase in temperatures and/or         pressures.     -   Proof: 6 wt % aqueous SO2 (sulfurous acid purchased from Sigma         Aldrich) was diluted to 0.3 wt % aqueous SO2 with DI water. The         0.3 wt % aqueous SO2 was mixed with 98% purity CaCO3(s)         (purchased from Sigma Aldrich) at room temperature and pressure.         0.3 wt % aqueous SO2 is within or less than the likely         concentration range of SO2 in the SO2-Rich solution based on SO2         solubility in water according to Henry's Law. Greater         concentrations than 0.3 wt % SO2(aq) are possible and 0.3 wt %         was tested as a conservative example. A gas forming reaction         occurred. Using FTIR, the resulting gas phase was determined to         comprise CO2. Using FTIR, the resulting solid phase was         determined to comprise CaSO3.         Reaction 2: Calcination or Thermal Decomposition of CaSO3 into         CaO and SO2         CaSO₃(s)⇒CaO(s)+SO₂(g)         ΔH=+226.3 kj/mol     -   Reaction occurs at or above 780° C.

Description: Reaction 2 involves producing CaO and regenerating the acid gas. Reaction 2 may involve the thermal decomposition of calcium sulfite into calcium oxide and sulfur dioxide. Reaction 2 may be conducted in the presence of other cement feedstocks. Reaction 2 may produce cement as an output instead of, or in addition to, calcium oxide. For example, the present reaction may be conducted in the presence of other cement feedstocks to produce cement or Portland cement. The present reaction may be conducted in a kiln or other system employed for calcination. The present reaction may be retrofitted into or conducted in infrastructure designed for the calcination of cement or calcium carbonate or limestone or a combination thereof. The present reaction may be facilitated by a carrier gas, which may comprise hot combustion gases or a hot recirculated carrier gas or a combination thereof.

Note: A portion of sulfur dioxide or other sulfur compounds may be absorbed or reacted into the solid material undergoing calcination and/or may be present in the calcined products or at least a portion of the calcined products.

Note: Sulfur dioxide may be absorbed into other cement feedstocks and/or the calcined products if, for example, the present reaction is employed for the production of cement. Sulfur dioxide exiting the calciner as gaseous sulfur dioxide may comprise less sulfur dioxide than the amount of sulfur dioxide in the form of ‘sulfite’ present in the calcium sulfite input.

Conditions: The present thermal decomposition reaction may be conducted at elevated temperatures, which may include, but is not limited to, temperatures greater than 700° C., or greater than 720° C., or greater than 750° C., or greater than 780° C. The temperature range of the present reaction may be similar to the temperature range employed in the calcination of calcium carbonate. Heat may be supplied to power the thermal decomposition process, by, for example, including, but not limited to, hot combustion flue gases or hot carrier gases or a combination thereof, which may be passed over or through or in direct contact with the calcium sulfite. It may be desirable for the present reaction to be conducted in a low diatomic oxygen or diatomic oxygen free environment to, for example, prevent the formation of relatively permanent sulfur oxides, such as sulfates and/or sulfur trioxide. For example, said hot combustion flue gases may possess low concentrations of diatomic oxygen or may be diatomic oxygen free. If the reaction yield in ‘Reaction 1’ is less than 100%, there may be calcium carbonate present in the input calcium sulfite. Some calcination conditions of the calcium sulfite may be similar and/or applicable to the calcination conditions employed for calcium carbonate, enabling residual calcium carbonate to be thermally decomposed into calcium oxide and/or cement simultaneous to the thermal decomposition of calcium sulfite into calcium oxide during ‘Reaction 2’.

The present reaction step may be conducted in the presence of clay, silicates or other reagents or materials present in a cement kiln during the production of cement, or a combination thereof. For example, calcium sulfite may be employed as a substitute for a portion of the calcium carbonate or calcium oxide or a combination thereof employed as an input feedstock during the production of cement. The resulting cement may comprise the same or similar composition or properties to Portland cement or other cements known in the art. The resulting cement may comprise the same or similar or superior properties to cements known in the art.

The present invention and/or the present reaction step may comprise a process for the production of cement. Said cement may comprise Portland cement. Said cement may comprise calcium oxide or other oxide salt, which may be carbonated or hydrated or otherwise reacted in a manner during the curing of said cement or plaster.

Proof: The thermal decomposition temperature and enthalpy of formation of calcium sulfite are documented in literature. Cubicciotti et al. (Cubicciotti, D., Sanjurjo, A., & Hildenbrand, D. L. (1977). The thermal decomposition of CaSO3 and its enthalpy of formation. Journal of The Electrochemical Society, 124(6), 933) determined the decomposition temperature of calcium sulfite is 723° C. to 767° C. and its enthalpy of formation is −277 Kcal per mole, or −1159 kJ per mole. Matsuzaki et al. (Matsuzaki, R., Masumizu, H., Murakami, N., & Saeki, Y. (1978). The Thermal Decomposition Process of Calcium Sulfite. Bulletin of the Chemical Society of Japan, 51(1), 121-122. doi:10.1246/bcsj.51.121) found calcium sulfite starts decomposing at 640° C. and fully decomposes into calcium oxide and sulfur dioxide above 780° C.

Reaction 3: Absorption of SO2 into SO2-Lean Solution, Recovering SO2 SO₂(g)+SO₂(lean aq)⇔SO₂(rich aq) ΔH=−23.2 kj/mol

-   -   Absorption may occur at, for example, room temperature         conditions or relatively cool conditions

Description: Reaction 3 involves absorbing acid gas or separating acid gas from a gas mixture or a combination thereof. Reaction 3 may involve absorbing sulfur dioxide into an aqueous solution, separating at least a portion of the sulfur dioxide from a gas mixture, which may comprise post-combustion gases or flue gases. The resulting sulfur dioxide rich aqueous solution may comprise a suitable form of sulfur dioxide to employed in Reaction 1. At least a portion or all of the sulfur dioxide absorbed in Reaction 3 may be employed in Reaction 1. Sulfur dioxide may be reused internally, as may, for example, be expressed in Reactions 1-3. SO2(aq) from Reaction 3 may comprise the same SO2(aq) as is an input to Reaction 1.

The present reaction and/or the entire process may benefit or harness the greater solubility of SO2(aq) in water relative to carbon dioxide and/or the ability for SO2 to be continuously recirculated in the system. Unlike carbon dioxide, at gas partial pressures less than 1 atm and temperatures above 0° C., sulfur dioxide is soluble in water and may form a solution with a substantial concentration of dissolved SO2 (e.g. greater than 0.01 wt %). For example, 10 vol % SO2 in a gas stream with a total pressure of 1 atm can dissolve in water to form a solution with 0.826 wt % SO2 at 25° C. (according to Henry's Law), while a 10 vol % CO2 in a gas stream with a total pressure of 1 atm can dissolve in water to form a solution with 0.014 wt % CO2 at 25° C. Based on Henry's Law, SO2 possesses about 59 times or 5,900% greater solubility in water than CO2. The significantly greater solubility of SO2 relative to CO2 may be leveraged in the present process to produce captured CO2 and/or valuable oxide salts and/or valuable other salts by, for example, including, but not limited to, the ability to separate SO2(g) from gas streams with relatively low partial pressures of SO2(g) through dissolution in water and/or the react the resulting SO2(aq) directly with a CO2-containing salt to produce high partial pressure CO2(g) and a thermally decomposable SO2-containing salt. Advantageously, SO2 can be regenerated from the 502-containing salt (such as Reactions 2 and 3) while producing a desired product oxide salt (Reaction 2).

Conditions: The present reaction or step may be conducted under conditions suitable or advantageous to enable the dissolution or absorption of an acid gas, such as SO2, into water or aqueous solution. For example, the present reaction may be conducted near or at or above atmospheric pressure and/or near or at or below atmospheric temperature. For example, the present reaction may conducted under conditions which may provide an desired or optimal balance between absorption rate and absorption capacity. For example, the present reaction may conducted under conditions which may provide greater absorption capacity, such as lower temperatures and/or greater pressures. For example, the present reaction may conducted under conditions which may provide greater absorption rate, such as higher temperatures and/or greater pressures. For example, the present reaction may conducted under conditions which are sufficiently cool to enable absorption capacity, such as, including, but is not limited to, one or more or a combination of the following temperature ranges: less than 100° C., or less than 90° C., or less than 80° C., or less than 70° C., or less than 60° C., or less than 50° C., or less than 40° C., or less than 30° C., or less than 25° C., or less than 20° C., or less than 15° C., or less than 10° C., or less than 5° C., or less than 0° C. For example, the present reaction may conducted under conditions which are sufficiently warm to prevent the formation of a solid phase, such as ice, which may include, but is not limited to, one or more or a combination of the following: greater than −15° C., greater than −10° C., greater than −5° C., or greater than 0° C. For example, the present reaction may be conducted with partial pressures or volume % concentrations or combinations thereof of acid gas which are sufficient to enable a sufficiently concentrated acid gas solution, which may include, but is not limited to, one or more or a combination of the following: greater than 10 PPM, or greater than 100 PPM, or greater than 1000 PPM, or greater than 0.1%, or greater than 0.5%, or greater than 1%, or greater than 2%, or greater than 3%, or greater than 4%, or greater than 5%, or greater than 6%, or greater than 7%, or greater than 8%, or greater than 9%, or greater than 10%.

Proof: According to Henry's Law, a 10 vol % SO2 in a gas stream with a total pressure of 1 atm can dissolve in water to form a solution with 0.826 wt % SO2(aq) at 25° C. 0.826 wt % SO2(aq) is a greater concentration than the weight-percent concentration of SO2(aq) in the experimental proof for Reaction 1.

Note: A sufficiently concentrated acid gas solution may comprise a solution with a concentration of dissolved acid gas comprising greater than or equal to one or more or a combination of the following concentrations: 0.0001 wt %, or 0.001 wt %, or 0.01 wt %, or 0.05 wt %, or 0.1 wt %, or 0.2 wt %, or 0.3 wt %, or 0.4 wt %, or 0.5 wt %, or 0.6 wt %, or 0.7 wt %, or 0.8 wt %, or 0.9 wt %, or 1 wt %, or 1.1 wt %, or 1.2 wt %, or 1.3 wt %, or 1.4 wt %, or 1.5 wt %, or 1.6 wt %, or 1.7 wt %, or 1.8 wt %, 1.9 wt %, or 2.0 wt %, or 2.5 wt %, or 3 wt %, or 3.5 wt %, or 4 wt %, or 4.5 wt %, or 5 wt %.

Note: During or before or after one or more or a combination of the above reactions, a portion of the sulfur oxides may be exposed to oxygen and may form a portion of more permanent oxides, such as sulfates or sulfur trioxide. Said exposure to diatomic oxygen may be inadvertent or incidental or unintentional or accidental. The presence of more permanent sulfur oxides may have a minimal impact or may be beneficial to the output calcium oxide or cement, especially if said more permanent sulfur oxides exist at a relatively low concentration. A relatively low concentration may include, but is not limited to, one or more or a combination of the following: less than 1 wt %, or less than 2 wt %, or less than 3 wt %, or less than 4 wt %, or less than 5 wt %, or less than 6 wt %, or less than 7 wt %, or less than 8 wt %, or less than 9 wt %, or less than 10 wt %, or less than 15 wt %, or less than 20 wt %, or less than 30 wt %, or less than 40 wt %, or less than 50 wt %.

Reactions Requiring Heat Heat Input Required CaSO₃(s) ⇒ CaO(s) + SO₂(g) ${\Delta H} = {{+ 226.3}\frac{kJ}{mol}}$ or 4,035.5 MJ per Metric Ton of CaO Total 4,035.5 MJ per Metric Ton of CaO

Comparison of Heat Input Required Reaction CaSO₃(s) ⇒ CaO(s) + CaCO₃(s) ⇒ CaO(s) + (Representative of SO₂(g) CO₂(g) Type of Process) Heat Input >780° C. >900° C. Temperature Heat Input Required ${\Delta H} = {{+ 226.3}\frac{kJ}{mol}}$ ${\Delta H} = {{+ 172}\frac{kJ}{mol}}$ or or 4,035.5 MJ per Metric 3,067.2 MJ per Metric Ton CaO Ton CaO CO2 Emissions

Comparison of CO₂ Emissions by Reaction Reaction CaSO₃(s) ⇒ CaO(s) + CaCO₃(s) ⇒ CaO(s) + (Representative of SO₂(g) CO₂(g) Type of Process) Heat Input >780° C. >900° C. Temperature Heat Input Required ${\Delta H} = {{+ 226.3}\frac{kJ}{mol}}$ ${\Delta H} = {{+ 172}\frac{kJ}{mol}}$ or 4,035.5 MJ per or 3,067.2 MJ per Metric Ton CaO Metric Ton CaO CO₂ Emissions 0.199 Metric Ton CO₂ 0.151 Metric Ton CO₂ from Heat (if Fuel per Metric Ton CaO per Metric Ton CaO is Natural Gas) CO₂ Emissions 0.618 Metric Ton CO₂ 0.470 Metric Ton CO₂ from Heat (if Fuel per Metric Ton CaO per Metric Ton CaO is Coal) CO₂ Emissions 0 Metric Ton CO₂ per 0 Metric Ton CO₂ per from Heat (if Fuel Metric Ton CaO Metric Ton CaO is Carbon-Free) CO₂ Emissions 0 Metric Tons CO₂ per 0.784 Metric Ton CO₂ from Thermal Metric Ton CaO per Metric Ton CaO Decomposition Reaction Total CO₂ 0.199 Metric Ton CO₂ 0.935 Metric Ton CO₂ Emissions (if per Metric Ton CaO per Metric Ton CaO Natural Gas is Fuel) Total CO₂ 0.618 Metric Ton CO₂ 1.254 Metric Ton CO₂ Emissions (if Coal per Metric Ton CaO per Metric Ton CaO is Fuel) Total CO₂ 0 Metric Ton CO₂ per 0.784 Metric Ton CO₂ Emissions (if Fuel Metric Ton CaO per Metric Ton CaO is Carbon-Free)

Note: CO2 emissions may be net negative if the full lifecycle, including the absorption of CO2 from the air during downstream uses of CaO, such as in cement, non-hydraulic cement, plaster, or quicklime.

Note: CO2 emissions from the production of CaSO3 may be net zero because, for example, the CO2 generated from the reaction converting CaCO3 to CaSO3 is high purity, captured CO2, which may be directly employed in utilization, conversion, and/or sequestration.

Cost of Inputs, Value of Outputs, and Operating Profit

Cost of Inputs, Value of Outputs, and Operating Profit Reaction (Representative of Type of Process) CaSO₃(s) ⇒ CaO(s) + SO₂(g) CaCO₃(s) ⇒ CaO(s) + CO₂(g) Inputs and Cost of 1.783 Metric Tons of CaCO₃ = 1.783 Metric Tons of CaCO₃ = Inputs $89.15 $89.15 0.199 Metric Tons of Nat. Gas = 0.151 Metric Tons of Nat. Gas = $10.38 $7.87 Total Cost $99.53 $97.02 (Inputs) per metric ton of CaO Produced per metric ton of CaO Produced Outputs and 1 Metric Tons of CaO = $117.80 1 Metric Tons of CaO = $117.80 Value of Outputs 0.784 Metric Tons of Pure CO₂ = 0.784 Metric Tons CO₂ Flue Gas = $27.21 (without 45Q) $0 0.784 Metric Tons of Pure CO₂ = $54.42 (with 45Q) Total Value $145.02 (without 45Q) $117.80 (Outputs) per metric ton of CaO Produced per metric ton of CaO Produced $172.23 (with 45Q) per metric ton of CaO Produced Net Profit $45.49 (without 45Q) $20.78 per metric ton of CaO Produced per metric ton of CaO Produced $72.70 (with 45Q) per metric ton of CaO Produced Example Figure Descriptions

FIG. 1: Embodiment of a process for continuous production of CaO from CaCO3 or limestone or other typical CaO feedstocks. SO2 is provided as an example regenerable acid gas.

FIG. 2: Embodiment comprising a process for producing CaO from CaSO3. The present embodiment may comprise a portion of an overall process for the production of CaO from CaCO3 or limestone or other typical CaO feedstocks. For example, the present embodiment may comprise a portion of an overall process for the production of CaO wherein other portions of the process may comprise a batch or semi-batch or continuously stirred reactor (CSTR) or continuous process or a combination thereof, such as embodiments shown in FIGS. 3A-3C.

FIG. 3A: Embodiment comprising a process for producing CaSO3 and CO2 from CaCO3 and SO2. For example, the present embodiment may comprise a portion of an overall process for the production of CaO from CaCO3 and may comprise the present figure combined with FIG. 2. The present figure may comprise a batch or semi-batch or semi-continuous configuration. The present figure may show the present embodiment in a stage of a sequence of stages.

For example, the stages in a sequence may comprise:

-   1. First Stage: CaCO3 may be added to the first reactor (‘16’) -   2. Second Stage: H2SO3 or SO2(aq) or dissolved SO2 or liquid SO2 or     gaseous SO2 or SO2 or a combination thereof may be added to the     second reactor (‘39’) which may result in the production of CO2 and     the formation of CaSO3(s) -   3. Third Stage: CaSO3(s) and remaining water or remaining solution     may be drained or removed from the third reactor (‘55’). The     CaSO3(s) may be separated (‘61’) from the remaining water or     solution.

FIG. 3B: Same embodiment as FIG. 3A. The present figure shows each reactor undergoing a different stage than in FIG. 3A. In the present embodiment, the sequence of stages may comprise multiple stages. For example, the present embodiment may involve the sequence of stages described in the figure description of FIG. 3A.

FIG. 3C: Same embodiment as FIG. 3A. The present figure shows each reactor undergoing a different stage than in FIG. 3A. In the present embodiment, the sequence of stages may comprise multiple stages. For example, the present embodiment may involve the sequence of stages described in the figure description of FIG. 3A.

Example Figure Keys

Example FIG. 1 Key # Process Element Descriptions 1 Air Input - Air or other gas comprising at least a portion oxygen. 2 Gas Blower or Air Blower or Other Air Pump - Pump or Fan or Blower to pressurize or transfer or a combination thereof air or other gas comprising at least a portion oxygen into the system. 3 Air Post ‘2’ - Air or other gas comprising at least a portion oxygen after the gas blower. The temperature of ‘3’ may be similar to the temperature of the air source or the surrounding outside air temperature. The temperature of ‘3’ may be less than the temperature in ‘5’. 4 Heat Exchanger or Contact Heat Exchanger or Lime Cooler- ‘3’, which may comprise air, may be heat exchanged with hot CaO (‘26’), which may result in pre- heated air and cooled CaO. ‘3’ may be directly contacted with the CaO, cooling the CaO, while heating the air. If the air or other oxygen containing gas is in direct contact with CaO, it may be desirable to prevent the air or other oxygen containing gas from entering ‘10’ or other environment potentially containing sulfur oxides or recoverable sulfur oxides to prevent, for example, oxidation of SO₂ and/or sulfite into SO₃ and/or sulfate. Alternatively, or additionally, ‘3’ may be indirectly contacted or heat exchanged with the CaO, cooling the CaO, while heating the air. 5 Pre-Heated Air - Air which may have been preheated by in ‘4’. ‘5’ may comprise the air fed into the combustion or fuel burning process. 6 Carbonaceous Fuel Input - A fuel comprising carbon (‘6’) may be fed or injected into a fuel firing or combustion step (‘8’). Carbonaceous fuel may include, but is not limited to, natural gas, coal, pulverized coal, biomass, charcoal, oil, diesel, gasoline, kerosene, LPG, ethane, propane, butane, or a combination thereof. In some embodiments, it may be desirable to burn the carbonaceous fuel (‘6’) and/or sulfurous fuel (‘7’) at a ratio with oxygen such that minimal non-reacted oxygen or diatomic oxygen is present in post combustion gases (post-combustion gases may include, but are not limited to, ‘9’). 7 Sulfurous Fuel Input - A fuel comprising sulfur (‘7’) may be fed or injected into a fuel firing or combustion step (‘8’). Sulfurous fuel may include, but is not limited to, sulfur, elemental sulfur, sour gas, hydrogen sulfide, sulfur dioxide, sulfur monoxide, ammonium sulfate, ammonium sulfite, or a combination thereof. In some embodiments, it may be desirable to burn the sulfurous fuel (‘7’) and/or carbonaceous (‘6’) at a ratio with oxygen such that minimal non-reacted oxygen or diatomic oxygen is present in post combustion gases (for example - ‘9’). Sulfurous fuel may be employed to reduce the concentration of oxygen in the combustion gases. Sulfurous fuel may be employed to reduce the concentration of oxygen in the combustion gases instead of rich carbonaceous fuel - air ratios, preventing or minimizing incomplete combustion and/or the formation of carbon monoxide. Sulfurous fuel may be employed to as a make-up for any sulfur dioxide losses. Alternatively, or additionally, a nitrogenous fuel, such as ammonia or an ammonia salt or an ammonia derivative, may be employed introduced or combusted in ‘7’. 8 Combustion chamber or Firing Fan - A chamber or step for combusting fuel to generate high temperature gases for the calcination or thermal decomposition process. ‘8’ may be designed or optimized to minimize the concentration of oxygen in the combustion gases exiting ‘8’ and/or maximize combustion efficiency. 9 Input Hot Combustion Gases, SO₂-Lean - ‘9’ may comprise the hot combustion gases exiting ‘8’ and entering the calcination step or kiln or rotating kiln ‘10’. Although ‘9’ may contain sulfurous gases, such as sulfur dioxide, the concentration of the sulfurous gases in ‘9’ may desirably be lower than the concentration of sulfurous gases in the gases exiting the kiln, ‘11’. ‘9’ may possess minimal or ultra- low concentrations of diatomic oxygen to prevent or minimize the formation of sulfates and other practically permanent sulfur compounds or salts or further oxidized sulfur compounds. 10 Calcination Step or Kiln or Rotating Kiln - ‘10’ may comprise a kiln for the thermal decomposition of acid gas salts into ‘acid-gas' and oxide salt. For example, ‘10’ may comprise a kiln for the thermal decomposition of calcium sulfite into sulfur dioxide and calcium oxide. ‘10’ may comprise a rotating kiln or other kiln. Applicable kilns may include, but are not limited to, kilns employed in the art for the calcination of limestone, or calcination of calcium carbonate, or the production of cement, or a combination thereof. Calcium sulfite may be fed into the kiln and thermally decomposed into at least a portion of sulfur dioxide and calcium oxide using heat from, for example, hot combustion gases, ‘9’, which may be directly passed through or over or in direct contact with said calcium sulfite. Warm calcium oxide, ‘26’, and SO₂-Rich flue gases or combustion gases, ‘11’, may comprise outputs of ‘10’. 11 Hot Flue Gases, SO₂-Rich - ‘11’ may comprise the hot flue gases exiting the kiln, ‘10’. ‘11’ may comprise a high concentration of SO₂ due to, for example, the thermal decomposition or calcination of calcium sulfite in the kiln, ‘10’, and the SO₂ present in the Input Hot Combustion Gases, ‘9’. At least a portion or all of said ‘SO₂’, may be recovered, recycled internally, and/or removed from the gases in ‘11’ in subsequent steps before at least a portion of the gases in ‘11’ exit the process. ‘11’ may also comprise particulates which may require separation or removal from the gas stream in subsequent steps. 12 Heat Exchanger or Contact Heat Exchanger or Calcium Sulfite Pre-Heater - ‘11’, which may comprise SO₂-Rich hot flue gases, may be heat exchanged with cold calcium sulfite (‘24’), which may result in pre-cooled SO₂-Rich flue gases, ‘13’, and pre-heated CaSO₃, ‘25’. SO₂-Rich hot flue gases may be directly contacted with the CaSO₃. The SO₂-Rich hot flue gases may be directly contacted with the CaSO₃, for example, because the SO₂-Rich hot flue gases may possess an ultra-low concentration of diatomic oxygen, which may prevent the CaSO₃ from oxidizing into a sulfate and may facilitate the heating and/or decomposition of CaSO₃. 13 Pre-Cooled SO₂-Rich Flue Gas - ‘13’ may comprise pre-cooled SO₂-Rich flue gas, which may possess particulates which may need to be, at least in part, removed before the SO₂ absorption column, ‘16’. ‘13’ may undergo additional cooling before or during ‘14’. An additional gas blower may be required to transfer ‘13’, which may not be shown in a figure. 14 Particulate Remover or Baghouse or Electrostatic Precipitator, or Filter, or a combination thereof - ‘14’ may comprise one or more or a combination of steps to remove particulate matter from ‘13’. 15 Pre-Cooled SO₂-Rich Flue Gas after Particulate Removal - ‘15’ may comprise pre- cooled SO₂-Rich flue gas with at least a portion or most of the particulates removed relative to ‘13’. ‘15’ may undergo additional cooling or treatment before entering the SO₂ absorption column or absorption step, ‘16’. 16 SO₂ Absorption Column - ‘16’ may comprise an absorption column or contactor which facilitates the absorption of SO₂ from SO₂-Rich Flue Gas (‘15’) into an SO₂- Lean aqueous solution (‘28’), forming an SO₂ - rich aqueous solution (‘29’) and an SO₂-Lean Flue Gas Stream (‘17’). It may be desirable for ‘16’ to selectively absorb SO₂, while minimally absorbing CO₂. Water or water scrubbing may be employed to selectively absorb SO₂, while minimally absorbing CO₂ due to the significantly greater solubility of SO₂ in water than CO₂. 17 SO₂-Lean Flue Gas after SO₂ Absorption - ‘17’ may comprise SO₂-Lean flue gas following the absorption of SO₂ in ‘16’. ‘17’ may undergo additional treatment before exiting the process, ‘18’. 18 SO₂ Scrubbing and/or Other Further Treatment - ‘18’ may comprise an SO₂ scrubbing step to remove most of or practically all the remaining or residual SO₂ in ‘17’, which may result in an SO₂ ultra-lean flue gas stream, ‘19’. ‘18’ may involve a scrubbing process which selectively absorbs dilute concentrations of SO₂, while minimally absorbing CO₂. For example, the absorption solution may comprise a bicarbonate, or carbonate, or carbamate, or combination thereof salt or a mixture of salts. For example, the absorbent and/or adsorbent may comprise one or more absorbents and/or adsorbents known in the art for removing SO₂ and/or other acid gases from flue gas streams or gas streams. ‘18’ may comprise a regenerable scrubbing process, which may involve recovering or capturing SO₂ and/or other acid gases for recycle within the process or for other use. ‘18’ may comprise a non- regenerable scrubbing process, which may involve production and disposal of, for example, salts comprising SO₂. 19 SO₂ ultra-lean flue gas stream. ‘19’ may be vented. ‘19’ may undergo additional treatment. ‘19’ may undergo, for example, flue gas CO₂ capture. Although flue gas CO₂ capture is feasible, in the present invention, the total CO₂ in flue gas emissions may be substantially lower than the total CO₂ captured in other process steps (for example, the captured CO₂ in ‘34’) 20 ‘20’ may comprise an input of a CO₂ containing salt or a salt comprising CO₂. For example, ‘20’ may comprise calcium carbonate input. 21 ‘21’ may comprise a reactor or mixing apparatus. ‘21’ may be employed to react a salt comprising CO₂ (such as calcium carbonate) with a recoverable acid gas or a solution comprising a recoverable acid gas (such as aqueous sulfur dioxide). ‘21’ may involve the generation of high partial pressure ‘captured’ carbon dioxide, which may be generated during a reaction of a salt comprising CO₂ (such as calcium carbonate) with a recoverable acid gas or a solution comprising a recoverable acid gas (such as aqueous sulfur dioxide). The headspace of ‘21’ may comprise CO₂. It may be desirable for the headspace of ‘21’ to contain a high concentration of CO₂ or comprise almost entirely CO₂ and/or water vapor and/or acid gas vapor pressure to, for example, minimize downstream processing of captured CO₂. ‘21’ may operate in a continuous, semi-batch, or batch or combination thereof configuration. 22 ‘22’ may comprise a mixture of acid-gas rich salt and a fluid. For example, ‘22’ may comprise a mixture of solid calcium sulfite and water, which may comprise a solid- liquid mixture. ‘22’ may comprise some reactions which have not reached full yield or may be designed to be in excess or stoichiometric excess. For example, ‘22’ may comprise calcium carbonate and/or sulfur dioxide and/or aqueous sulfur dioxide. 23 ‘23’ may comprise a fluid - solid separation device. For example, ‘23’ may comprise a liquid-solid separation device or a gas-solid separation device or a liquid-gas separation device or a combination thereof. For example, ‘23’ may comprise, including, but not limited to, one or more or a combination of the following: a filter, a rotary filter, a centrifuge, a decanter, or a sedimentation separator. ‘23’ may involve separating solid salts, such as calcium sulfite and calcium carbonate, from water or remaining aqueous acid gas solution or acid gas or a combination thereof. 24 ‘24’ may comprise separated solid. ‘24’ may comprise separated calcium sulfite or calcium carbonate or a combination thereof. ‘24’ may be transferred to one or more steps involving pre-treatment, pre-heating, or calcination or thermal decomposition. For example, ‘24’ may undergo drying or further drying before or during or after entering ‘12’. It may be desirable for said drying, if any, to involve minimal or no contact with diatomic oxygen to, for example, prevent the oxidation of sulfite to sulfate. For example, said drying may comprise, including, but not limited to, one or more or a combination of the following: desiccants, or dry carrier gas, or warm carrier gas, or heated carrier gas, or centrifugation, or heating. 25 ‘25’ may comprise pre-heated solid salt, which may comprise at least a portion a salt comprising acid gas. For example, ‘25’ may comprise a pre-heated solid comprising calcium sulfite. ‘25’ may comprise pre-heated solid undergoing transferring to a calcination or thermal decomposition or cement production reaction or oxide salt formation reaction or gas formation reaction or a combination thereof step. 26 ‘26’ may comprise a calcined product. For example, ‘26’ may comprise calcium oxide, or Portland cement, or cement, or magnesium oxide or a combination thereof. ‘26’ may be warm due to exiting a thermal decomposition or calcination process. ‘26’ may be lean or contain a substantially lower concentration of sulfur dioxide or acid gas or recoverable acid or carbon dioxide or a combination thereof than ‘25’. ‘26’ may contain residual sulfite or sulfate or other sulfur or acid gas or may contain residual carbon dioxide salts or a combination thereof. 27 ‘27’ may comprise cooled calcined product. ‘27’ may exit the process and may be sold or otherwise utilized. ‘27’ may undergo further treatment if desired. 28 ‘28’ may comprise acid gas lean or sulfur dioxide lean water or solution. ‘28’ may be transferred to ‘16’ for absorption or bulk absorption of acid gas or sulfur dioxide. ‘28’ may be cooled before being contacted with acid gases or before entering ‘16’. Said cooling may involve recovering heat from ‘28’, which may include, but is not limited to, process heating, space heating, or other applications for heat. Said cooling may involve a chiller or chilled water or air cooling or wet surface contact cooling or other cooling methods or a combination thereof or one or more or a combination of processes for cooling. 29 ‘29’ may comprise an acid gas rich or sulfur dioxide rich water or solution. ‘29’ may comprise a sulfur dioxide rich solution resulting from the absorption of sulfur dioxide into water in an absorption column or gas-liquid contactor. ‘29’ may comprise an acid gas rich solution. 30 ‘30’ may comprise sulfur dioxide lean or other acid gas lean solution. ‘30’ may be lean in sulfur dioxide due to the reaction of aqueous sulfur dioxide with calcium carbonate. If present embodiment is operating in a continuous or semi-continuous fashion, ‘30’ may be lean in sulfur dioxide due to originating from or being transferred from a section or portion of ‘21’ which may possess solution with the greatest or a greater average contact time with calcium carbonate or other salt comprising carbon dioxide. 31 ‘31’ may comprise a solution or liquid phase separated following a solid-liquid separation step (for example: ‘23’). ‘31’ may comprise a lean concentration of acid gas or dissolved SO₂. ‘31’ may comprise a middle concentration of acid gas or dissolved SO₂. ‘31’ may be recirculated (‘32’) into a reactor or mixer and/or may be employed as a solution (‘33’) transferred or mixed with a solution to be employed as an absorption solution. The proportion of ‘31’ recirculated relative to employed as an absorption solution may be dependent on the relative concentration of dissolved acid gas in ‘31’, which may be monitored or measured with, for example, one or more or a combination of monitoring or measuring devices. 32 ‘32’ may comprise ‘31’ undergoing recirculation to a reactor or mixing vessel. 33 ‘33’ may comprise ‘31’ being transferred as a portion of an absorption solution. It may be desirable to mix ‘33’ with ‘30’. Alternatively, or additionally, ‘33’ may be transferred directly an absorption column (‘16’), wherein ‘33’ may enter or may be fed into the absorption column at a different point than ‘30’ or ‘28’. For example, if ‘33’ possesses a greater concentration of acid gas or SO₂ than ‘28’ or ‘30’, it may be desirable to add ‘33’ to an absorption column at a lower height or lower point in the absorption column. For example, it may be desirable to add ‘33’ at a point in the absorption column where the concentration of dissolved acid gas in the absorption solution may be similar to the concentration of dissolved acid gas in ‘33’. 34 ‘34’ may comprise a gas stream exiting a reactor or mixer, ‘21’. ‘34’ may comprise relatively high-pressure CO₂ or a gas stream comprising CO₂. If desirable, ‘34’ may exit ‘21’ at a relatively standard temperature and with a relatively low partial pressure of water vapor and/or other non-CO₂. 35 ‘35’ may comprise a compression and/or treatment step and/or liquification step. ‘35’ may comprise a compression and/or water or other solvent vapor removal step and/or residual acid gas or SO₂ removal step and/or gas cooling step and/or gas heating step and/or gas liquification step and/or gas processing step. ‘37’ may involve producing a supercritical fluid. 36 ‘36’ may comprise a fluid stream being transferred to undergo further treatment, compression or use. ‘36’ may comprise CO₂. 37 ‘37’ may comprise a compression and/or treatment and/or liquification step. ‘37’ may comprise a compression and/or water or other solvent vapor removal step and/ or residual acid gas or SO₂ removal step and/or gas cooling step and/or gas heating step and/or gas liquification step and/or gas processing step. ‘37’ may involve producing a supercritical fluid. 38 ‘38’ may comprise captured CO₂ under suitable conditions or at a suitable phase for, for example, transport, use, utilization, conversion, or storage.

Example FIG. 2 and FIG. 3 Key # Process Element Descriptions 1 Pre-Cooled SO₂-Rich Flue Gas after Particulate Removal - ‘1’ may comprise pre- cooled SO₂-Rich flue gas with at least a portion or most of the particulates removed. ‘1’ may undergo additional cooling or treatment before entering the SO₂ absorption column or absorption step, ‘2’. ‘1’ may undergo compression or pressurization before or while entering the absorption column or absorption step, ‘2’. 2 SO₂ Absorption Column - ‘2’ may comprise an absorption column or contactor which facilitates the absorption of SO₂ from SO₂-Rich Flue Gas (‘1’) into an SO₂-Lean solution (‘30’), forming an SO₂ - rich solution (‘6’) and a SO₂-Lean Flue Gas Stream (‘3’). It may be desirable for ‘2’ to selectively absorb SO₂, while minimally absorbing CO₂. Water or solvent scrubbing may be employed to selectively absorb SO₂, while, for example, minimally absorbing CO₂ due to the significantly greater solubility of SO₂ in water or other solvent than CO₂. 3 SO₂-Lean Flue Gas after SO₂ Absorption - ‘3’ may comprise SO₂-Lean flue gas following the absorption of SO₂ in ‘2’. ‘3’ may undergo additional treatment before exiting the process, ‘4’. 4 SO₂ Scrubbing and/or Other Further Treatment - ‘4’ may comprise a SO₂ scrubbing step to remove most of or practically all the remaining or residual SO₂ in ‘3’, which may result in an SO₂ ultra-lean flue gas stream, ‘5’. ‘4’ may involve a scrubbing process which selectively absorbs dilute concentrations of SO₂, while minimally absorbing CO₂. For example, the absorption solution may comprise a bicarbonate, or carbonate, or carbamate, or combination thereof salt or a mixture of salts. For example, the absorbent and/or adsorbent may comprise one or more absorbents and/or adsorbents known in the art for removing SO₂ and/or other acid gases from flue gas streams or gas streams. ‘4’ may comprise a regenerable scrubbing process, which may involve recovering or capturing SO₂ and/or other acid gases for recycle within the process or for other use. ‘4’ may comprise a non-regenerable scrubbing process, which may involve production and disposal of, for example, salts or chemicals comprising or deriving from SO₂. 5 SO₂ ultra-lean flue gas stream. ‘5’ may be vented. ‘5’ may undergo additional treatment. ‘5’ may undergo, for example, flue gas CO₂ capture. Although flue gas CO₂ capture is feasible, in the present invention, the total CO₂ in flue gas emissions may be substantially lower than the total CO₂ captured in other process steps (for example, the captured CO₂ in ‘23’). 6 ‘6’ may comprise an acid gas rich or sulfur dioxide rich water or solution. ‘6’ may comprise a sulfur dioxide rich solution resulting from the absorption of sulfur dioxide into water in an absorption column or gas-liquid contactor. ‘6’ may comprise an acid gas rich solution. 7 ‘7’ may comprise a multidirectional valve. ‘7’ may direct the flow of the sulfur dioxide rich solution, ‘6’, to the appropriate reactor. The sulfur dioxide rich solution may be directed to an appropriate reactor which may be at a stage in the batch or semi-batch sequence which involves the addition of sulfur dioxide rich solution. The appropriate reactor may change depending on the batch or semi-batch reaction stages and reaction sequence and each reactor's stage in the sequence. 8 ‘8’ may comprise sulfur dioxide rich solution directed to the first reactor. 9 ‘9’ may comprise a valve or redundant valve or a flow control valve or a pressure control valve or a pump or a combination thereof. 10 ‘10’ may comprise sulfur dioxide rich solution directed to the first reactor. 11 ‘11’ may comprise an input of a CO₂ containing salt or a salt comprising CO₂. For example, ‘11’ may comprise calcium carbonate input. 12 ‘12’ may comprise a multidirectional solid transfer valve or solid flow control or solid flow director. ‘12’ may direct the flow of the carbon dioxide salt, such as calcium carbonate, to the appropriate reactor. The carbon dioxide salt, such as calcium carbonate, may be directed to an appropriate reactor which is at a stage in the batch or semi-batch sequence which involves the addition of carbon dioxide salt. The appropriate reactor may change depending on the batch or semi-batch reaction stages and reaction sequence and each reactor's stage in the sequence. 13 ‘13’ may comprise carbon dioxide salt directed to the first reactor. 14 ‘14’ may comprise a valve or redundant valve or a flow control valve or a pressure control valve or a pump or a conveyer belt or a combination thereof. 15 ‘15’ may comprise carbon dioxide salt directed to the first reactor. 16 ‘16’ may comprise a reactor or mixing apparatus. ‘16’ may be employed to react a salt comprising CO₂, such as calcium carbonate, with a recoverable acid gas or a solution comprising a recoverable acid gas, such as aqueous sulfur dioxide. ‘16’ may involve the generation of high partial pressure ‘captured’ carbon dioxide, which may be generated during a reaction of a salt comprising CO₂, such as calcium carbonate, with a recoverable acid gas or a solution comprising a recoverable acid gas, such as aqueous sulfur dioxide. The headspace of ‘16’ may comprise CO₂. It may be desirable for the headspace of ‘16’ to contain a high concentration of CO₂ or comprise almost entirely CO₂ and/or water vapor and/or physical solvent vapor and/or acid gas vapor pressure to, for example, minimize downstream processing of captured CO₂. ‘16’ may operate in a semi-batch, or batch or combination thereof configuration. 17 ‘17’ may comprise a gas stream exiting a reactor or mixer, ‘16’. ‘17’ may comprise relatively high-pressure CO₂ or a gas stream comprising CO₂. If desirable, ‘17’ may exit ‘16’ at a relatively standard temperature and with a relatively low partial pressure of water vapor and/or other non-CO₂. 18 ‘18’ may comprise a multidirectional valve. ‘18’ may direct a gas stream comprising CO₂ from one or more reactors to CO₂ processing, treatment, compression, transportation, utilization, and/or conversion steps. ‘18’ may control the flow of gas streams or gas streams comprising CO₂, including, for example, ensuring gas streams achieve the appropriate specifications or the reactor is at the appropriate stage or a combination thereof before or while directing one or more gas streams comprising CO₂. 19 ‘19’ may comprise a gas stream comprising CO₂ directed by ‘18’ to one or more or a combination of CO₂ processing, treatment, compression, transportation, utilization, and/or conversion steps. 20 ‘20’ may comprise a compression and/or treatment step and/or liquification step. ‘20’ may comprise a compression and/or water or solvent removal step and/or residual acid gas or SO₂ removal step and/or gas cooling step and/or gas heating step and/or gas liquification step and/or gas processing step. ‘20’ may involve producing a supercritical fluid. 21 ‘21’ may comprise a fluid stream being transferred to undergo further treatment, compression or use. ‘21’ may comprise CO₂. 22 ‘22’ may comprise a compression and/or treatment and/or liquification step. ‘22’ may comprise a compression and/or water or solvent removal step and/or residual acid gas or SO₂ removal step and/or cooling step and/or heating step and/or liquification step and/or processing step. ‘22’ may involve producing a supercritical fluid. 23 ‘23’ may comprise captured CO₂ under suitable conditions or at a suitable phase for, for example. transport, use, utilization, conversion, or storage. 24 ‘24’ may comprise a mixture of acid-gas rich salt and a fluid. For example, ‘22’ may comprise a mixture of solid calcium sulfite and water and/or physical solvent, which may comprise a solid-liquid mixture. ‘24’ may comprise some reagents which have not reached full yield or may be designed to be in excess or stoichiometric excess. For example, ‘24’ may comprise a portion calcium carbonate and/or sulfur dioxide and/or sulfur dioxide solution. 25 ‘25’ may comprise a fluid - solid separation device. For example, ‘25’ may comprise a liquid-solid separation device or a gas-solid separation device or a liquid-gas separation device or a combination thereof. For example, ‘25’ may comprise, including, but not limited to, one or more or a combination of the following: a filter, a rotary filter, a centrifuge, a decanter, or a sedimentation separator. ‘25’ may involve separating solid salts, such as calcium sulfite and calcium carbonate, from water or remaining acid gas solution or acid gas or a combination thereof. 26 ‘26’ may comprise a solution or liquid phase separated following a solid-liquid separation step (for example: ‘25’). ‘26’ may comprise a lean concentration of acid gas or SO₂ solution. ‘26’ may be lean in sulfur dioxide due to the reaction of sulfur dioxide with calcium carbonate. 27 ‘27’ may comprise a valve or redundant valve or a flow control valve or a pressure control valve or a pump or a combination thereof. 28 ‘28’ may comprise sulfur dioxide lean or other acid gas lean solution. 29 ‘29’ may comprise a multidirectional valve. ‘29’ may direct the flow of the sulfur dioxide lean solution to the sulfur dioxide absorption column or contactor, ‘2’. 30 ‘30’ may comprise acid gas lean or sulfur dioxide lean water or solution. ‘30’ may be transferred to ‘2’ for absorption or bulk absorption of acid gas or sulfur dioxide. ‘30’ may be cooled before being contacted with acid gases or before entering ‘2’. Said cooling may involve recovering heat from ‘30’, which may include, but is not limited to, process heating, space heating, or other applications for heat. Said cooling may involve a chiller or chilled water or air cooling or wet surface contact cooling or other cooling methods or a combination thereof or one or more or a combination of processes for cooling. 31 ‘31’ may comprise separated solid. ‘31’ may comprise separated calcium sulfite or calcium carbonate or a combination thereof. 32 ‘32’ may comprise a valve or redundant valve or a flow control valve or a pressure control valve or a pump or a conveyer belt or a combination thereof. 33 ‘33’ may comprise separated solid. ‘33’ may comprise separated calcium sulfite or calcium carbonate or a combination thereof. 34 ‘34’ may comprise a multidirectional solid transfer valve or solid flow control or solid flow director. ‘34’ may direct the flow of the separated acid gas salt or regenerable acid gas salt, such as calcium sulfite, subsequent treatment steps and/or thermal decomposition or calcination step. 35 ‘35’ may comprise separated solid. ‘35’ may comprise separated calcium sulfite or calcium carbonate or a combination thereof. ‘35’ may be transferred to one or more steps involving pre-treatment, pre-heating, or calcination or thermal decomposition. For example, ‘35’ may undergo drying or further drying before or during or after entering ‘79’. It may be desirable for said drying, if any, to involve minimal or no contact with diatomic oxygen to, for example, prevent the oxidation of sulfite to sulfate. For example, said drying may comprise, including, but not limited to, one or more or a combination of the following: desiccants, or dry carrier gas, or warm carrier gas, or heated carrier gas, or centrifugation, or heating. 36 ‘36’ may comprise sulfur dioxide rich solution directed to the second reactor. 37 ‘37’ may comprise a valve or redundant valve or a flow control valve or a pressure control valve or a pump or a combination thereof. 38 ‘38’ may comprise sulfur dioxide rich solution directed to the second reactor. 39 ‘39’ may comprise a reactor or mixing apparatus. ‘39’ may be employed to react a salt comprising CO₂, such as calcium carbonate, with a recoverable acid gas or a solution comprising a recoverable acid gas, such as aqueous sulfur dioxide or sulfur dioxide dissolved in a physical solvent. ‘39’ may involve the generation of high partial pressure ‘captured’ carbon dioxide, which may be generated during a reaction of a salt comprising CO₂, such as calcium carbonate, with a recoverable acid gas or a solution comprising a recoverable acid gas. The headspace of ‘39’ may comprise CO₂. It may be desirable for the headspace of ‘39’ to contain a high concentration of CO₂ or comprise almost entirely CO₂ and/or water vapor or solvent vapor and/or acid gas vapor pressure to, for example, minimize downstream processing of captured CO₂. ‘39’ may operate in a semi-batch, or batch or combination thereof configuration. 40 ‘40’ may comprise carbon dioxide salt directed to the second reactor. 41 ‘41’ may comprise a valve or redundant valve or a flow control valve or a pressure control valve or a pump or a conveyer belt or a combination thereof. 42 ‘42’ may comprise carbon dioxide salt directed to the third reactor. 43 ‘43’ may comprise a gas stream exiting a reactor or mixer, ‘39’. ‘43’ may comprise relatively high-pressure CO₂ or a gas stream comprising CO₂. If desirable, ‘43’ may exit ‘39’ at a relatively standard temperature and with a relatively low partial pressure of water vapor and/or other non-CO₂ contaminants. 44 ‘44’ may comprise a mixture of acid-gas rich salt and a fluid. For example, ‘44’ may comprise a mixture of solid calcium sulfite and water, which may comprise a solid- liquid mixture. ‘44’ may comprise some reagents which have not reached full yield or may be designed to be in excess or stoichiometric excess. For example, ‘44’ may comprise a portion calcium carbonate and/or sulfur dioxide and/or sulfur dioxide solution. 45 ‘45’ may comprise a fluid - solid separation device. For example, ‘45’ may comprise a liquid-solid separation device or a gas-solid separation device or a liquid-gas separation device or a combination thereof. For example, ‘45’ may comprise, including, but not limited to, one or more or a combination of the following: a filter, a rotary filter, a centrifuge, a decanter, or a sedimentation separator. ‘45’ may involve separating solid salts, such as calcium sulfite and calcium carbonate, from water or solvent or remaining acid gas solution or acid gas or a combination thereof. 46 ‘46’ may comprise a solution or liquid phase separated following a solid-liquid separation step (for example: ‘45’). ‘46’ may comprise a lean concentration of acid gas or aqueous SO₂ or SO2 solution. ‘46’ may be lean in sulfur dioxide due to the reaction of sulfur dioxide with calcium carbonate. 47 ‘47’ may comprise a valve or redundant valve or a flow control valve or a pressure control valve or a pump or a combination thereof. 48 ‘48’ may comprise sulfur dioxide lean or other acid gas lean solution. 49 ‘49’ may comprise separated solid. ‘49’ may comprise separated calcium sulfite or calcium carbonate or a combination thereof. 50 ‘50’ may comprise a valve or redundant valve or a flow control valve or a pressure control valve or a pump or a conveyer belt or a combination thereof. 51 ‘51’ may comprise separated solid. ‘51’ may comprise separated calcium sulfite or calcium carbonate or a combination thereof. 52 ‘52’ may comprise sulfur dioxide rich solution directed to the third reactor. 53 ‘53’ may comprise a valve or redundant valve or a flow control valve or a pressure control valve or a pump or a combination thereof. 54 ‘54’ may comprise sulfur dioxide rich solution directed to the third reactor. 55 ‘55’ may comprise a reactor or mixing apparatus. ‘55’ may be employed to react a salt comprising CO₂, such as calcium carbonate, with a recoverable acid gas or a solution comprising a recoverable acid gas. ‘55’ may involve the generation of high partial pressure ‘captured’ carbon dioxide, which may be generated during a reaction of a salt comprising CO₂, such as calcium carbonate, with a recoverable acid gas or a solution comprising a recoverable acid gas. The headspace of ‘55’ may comprise CO₂. It may be desirable for the headspace of ‘55’ to contain a high concentration of CO₂ or comprise almost entirely CO₂ and/or water vapor or solvent vapor and/or acid gas vapor pressure to, for example, minimize downstream processing of captured CO₂. ‘55’ may operate in a semi-batch, or batch or combination thereof configuration. 56 ‘40’ may comprise carbon dioxide salt directed to the third reactor. 57 ‘41’ may comprise a valve or redundant valve or a flow control valve or a pressure control valve or a pump or a conveyer belt or a combination thereof. 58 ‘42’ may comprise carbon dioxide salt directed to the third reactor. 59 ‘59’ may comprise a gas stream exiting a reactor or mixer, ‘55’. ‘59’ may comprise relatively high-pressure CO₂ or a gas stream comprising CO₂. If desirable, ‘59’ may exit ‘55’ at a relatively standard temperature and with a relatively low partial pressure of water vapor and/or solvent vapor and/or other non-CO₂. 60 ‘60’ may comprise a mixture of acid-gas rich salt and a fluid. For example, ‘60’ may comprise a mixture of solid calcium sulfite and water or solvent, which may comprise a solid-liquid mixture. ‘60’ may comprise some reagents which have not reached full yield or may be designed to be in excess or stoichiometric excess. For example, ‘60’ may comprise a portion calcium carbonate and/or sulfur dioxide and/or sulfur dioxide solution. 61 ‘61’ may comprise a fluid - solid separation device. For example, ‘61’ may comprise a liquid-solid separation device or a gas-solid separation device or a liquid-gas separation device or a combination thereof. For example, ‘61’ may comprise, including, but not limited to, one or more or a combination of the following: a filter, a rotary filter, a centrifuge, a decanter, or a sedimentation separator. ‘61’ may involve separating solid salts, such as calcium sulfite and calcium carbonate, from water or solvent or remaining acid gas solution or acid gas or a combination thereof. 62 ‘62’ may comprise a solution or liquid phase separated following a solid-liquid separation step (for example: ‘61’). ‘62’ may comprise a lean concentration of acid gas or dissolved SO₂. ‘62’ may be lean in sulfur dioxide due to the reaction of aqueous sulfur dioxide with calcium carbonate. 63 ‘63’ may comprise a valve or redundant valve or a flow control valve or a pressure control valve or a pump or a combination thereof. 64 ‘64’ may comprise sulfur dioxide lean or other acid gas lean solution. 65 ‘65’ may comprise separated solid. ‘65’ may comprise separated calcium sulfite or calcium carbonate or a combination thereof. 66 ‘66’ may comprise a valve or redundant valve or a flow control valve or a pressure control valve or a pump or a conveyer belt or a combination thereof. 67 ‘67’ may comprise separated solid. ‘67’ may comprise separated calcium sulfite or calcium carbonate or a combination thereof. 68 Air Input - Air or other gas comprising at least a portion oxygen. 69 Gas Blower or Air Blower or Other Air Pump - Pump or Fan or Blower to pressurize or transfer or a combination thereof air or other gas comprising at least a portion oxygen into the system. 70 Air Post ‘69’ - Air or other gas comprising at least a portion oxygen after the gas blower. The temperature of ‘70’ may be similar to the temperature of the air source or the surrounding outside air temperature. The temperature of ‘70’ may be less than the temperature of ‘72’. 71 Heat Exchanger or Contact Heat Exchanger or Lime Cooler- ‘70’, which may comprise air, may be heat exchanged with hot CaO or cement (‘83’), which may result in pre-heated air and cooled CaO or cement. ‘70’ may be directly contacted with the CaO or cement, cooling the CaO or cement, while heating the air. If the air or other oxygen containing gas is in direct contact with CaO or cement, it may be desirable to prevent the air or other oxygen containing gas from entering ‘77’ or other environment potentially containing sulfur oxides or recoverable sulfur oxides to prevent, for example, oxidation of SO₂ and/or sulfite into SO₃ and/or sulfate during, for example, thermal decomposition steps. Alternatively, or additionally, ‘70’ may be indirectly contacted or heat exchanged with the CaO or cement, cooling the CaO or cement, while heating the air. 72 Pre-Heated Air - Air which may have been preheated by in ‘71’. ‘72’ may comprise air fed into the combustion or fuel burning process. 73 Carbonaceous Fuel Input - A fuel comprising carbon (‘73’) may be fed or injected into a fuel firing or combustion step (‘75’). Carbonaceous fuel may include, but is not limited to, natural gas, coal, pulverized coal, biomass, charcoal, oil, diesel, gasoline, kerosene, LPG, ethane, propane, butane, or a combination thereof. In some embodiments, it may be desirable to burn the carbonaceous fuel (‘73’) and/or sulfurous fuel (‘74’) at a ratio with oxygen such that minimal non-reacted oxygen or diatomic oxygen is present in post combustion gases (post-combustion gases may include, but are not limited to, ‘76’). 74 Sulfurous Fuel Input - A fuel comprising sulfur (‘74’) may be fed or injected into a fuel firing or combustion step (‘75’). Sulfurous fuel may include, but is not limited to, sulfur, elemental sulfur, sour gas, hydrogen sulfide, sulfur dioxide, sulfur monoxide, ammonium sulfate, ammonium sulfite, or a combination thereof. In some embodiments, it may be desirable to burn the sulfurous fuel (‘74’) and/or carbonaceous (‘73’) at a ratio with oxygen such that minimal non-reacted oxygen or diatomic oxygen is present in post combustion gases (for example - ‘76’). Sulfurous fuel may be employed to reduce the concentration of oxygen in the combustion gases. Sulfurous fuel may be employed to reduce the concentration of oxygen in the combustion gases instead of rich carbonaceous fuel - air ratios, preventing or minimizing incomplete combustion and/or the formation of carbon monoxide. Sulfurous fuel may be employed to as a make-up for sulfur dioxide losses. Alternatively, or additionally, a nitrogenous fuel, such as ammonia or an ammonia salt or an ammonia derivative, may be employed introduced or combusted in ‘74’. 75 Combustion chamber or Firing Fan - A chamber or step for combusting fuel to generate high temperature gases for the calcination or thermal decomposition process. ‘75’ may be designed or optimized to minimize the concentration of oxygen in the combustion gases exiting ‘75’ and/or optimize combustion efficiency. 76 Input Hot Combustion Gases, SO₂-Lean - ‘76’ may comprise the hot combustion gases exiting ‘75’ and entering the calcination step or kiln or rotating kiln ‘77’ . Although ‘76’ may contain sulfurous gases, such as sulfur dioxide, the concentration of the sulfurous gases in ‘76’ may desirably be lower than the concentration of sulfurous gases in the gases exiting the kiln, ‘78’. ‘76’ may possess minimal or ultra- low concentrations of diatomic oxygen to prevent or minimize the formation of sulfates and other practically permanent sulfur compounds or salts or further oxidized sulfur compounds. 77 Calcination Step or Kiln or Rotating Kiln - ‘77’ may comprise a kiln for the thermal decomposition of acid gas salts into ‘acid-gas’ and oxide salt or cement. For example, ‘77’ may comprise a kiln which may be employed in the present invention for the thermal decomposition of calcium sulfite into sulfur dioxide and calcium oxide or cement. ‘77’ may comprise a rotating kiln or other kiln. Applicable kilns may include, but are not limited to, kilns employed in the art for the calcination of limestone, or calcination of calcium carbonate, or the production of cement, or a combination thereof. Calcium sulfite may be fed into the kiln and thermally decomposed into at least a portion of sulfur dioxide and calcium oxide or cement using heat from, for example, hot combustion gases, ‘76’, which may be directly passed through or over or in direct contact with said calcium sulfite. Warm calcium oxide or cement, ‘83’, and SO₂-Rich flue gases or combustion gases, ‘78’, may comprise outputs of ‘77’. 78 Hot Flue Gases, SO₂-Rich - ‘78’ may comprise the hot flue gases exiting the kiln, ‘77’. ‘78’ may comprise a relatively high concentration of SO₂ due to, for example, the thermal decomposition or calcination of calcium sulfite in the kiln, ‘77’, and/or SO₂ present in the Input Hot Combustion Gases, ‘76’. At least a portion or all of said ‘SO2’, may be recovered, recycled internally, and/or removed from the gases in ‘78’ in subsequent steps, which may be before at least a portion of the gases in ‘78’ exit the process or are vented. ‘78’ may also comprise particulates which may require separation or removal from the gas stream in subsequent steps. 79 Heat Exchanger or Contact Heat Exchanger or Calcium Sulfite Pre-Heater - ‘78’, which may comprise SO₂-Rich hot flue gases, may be heat exchanged with cold calcium sulfite (‘35’), which may result in pre-cooled SO₂-Rich flue gases, ‘80’, and pre-heated CaSO₃, ‘82’. SO₂-Rich hot flue gases may be directly contacted with the CaSO₃. The SO₂-Rich hot flue gases may be directly contacted with the CaSO₃, for example, because the SO₂-Rich hot flue gases may possess an ultra-low concentration of diatomic oxygen, which may prevent the CaSO₃ from oxidizing into a sulfate and/or may facilitate the heating and/or decomposition of CaSO₃. 80 Pre-Cooled SO₂-Rich Flue Gas - ‘80’ may comprise pre-cooled SO₂-Rich flue gas, which may possess particulates which may need to be, at least in part, removed before the SO₂ absorption column, ‘2’. ‘80’ may undergo additional cooling before or during ‘81’. An additional gas blower or compressor may be required to transfer ‘80’, which may not be shown in a figure. 81 Particulate Remover or Baghouse or Electrostatic Precipitator, or Filter, or a combination thereof- ‘81’ may comprise one or more or a combination of steps to remove particulate matter from ‘80’. 82 ‘82’ may comprise pre-heated solid salt, which may comprise at least a portion a salt comprising acid gas. For example, ‘82’ may comprise a pre-heated solid comprising calcium sulfite. ‘82’ may comprise pre-heated solid undergoing transferring to a calcination or thermal decomposition or cement production reaction or oxide salt formation reaction or gas formation reaction or a combination thereof step. 83 ‘83’ may comprise a calcined product. For example, ‘83’ may comprise calcium oxide, or Portland cement, or cement or magnesium oxide or a combination thereof. ‘83’ may be warm due to exiting a thermal decomposition or calcination process. ‘83’ may be lean or contain a substantially lower concentration of sulfur dioxide or acid gas or recoverable acid or carbon dioxide or a combination thereof than ‘83’. ‘83’ may contain residual sulfite or sulfate or other sulfur or acid gas or may contain residual carbon dioxide salts or a combination thereof. 84 ‘84’ may comprise cooled calcined product. ‘84’ may exit the process and may be sold or otherwise utilized. ‘84’ may undergo further treatment if desired. Alternatively, or additionally, ‘84’ may be employed to absorb CO₂ from the air or water or other gas or liquid stream comprising at least a portion CO₂ or acid gas. For example, ‘84’ may be employed to capture CO₂ if, for example, the present invention comprises at least a portion of a CO₂ air capture system. Additional General Description

One or more or a combination of steps in the present invention may be conducted in same location or region if desired.

One or more or a combination of steps in the present invention may be conducted in separate locations if desired. For example, a captured carbon dioxide production step, which may comprise a reaction of calcium carbonate with sulfur dioxide to produce calcium sulfite and carbon dioxide, may be conducted in a separate location from the calcining step, which may comprise calcining calcium sulfite into calcium oxide and/or cement and sulfur dioxide. For example, a captured carbon dioxide production step may be conducted in or near a location or application requiring or consuming carbon dioxide, which may include, but is not limited to, one or more or a combination of the following: carbon dioxide enhanced oil recovery, carbon dioxide sequestration, carbon dioxide conversion into materials or chemicals, agriculture, carbon dioxide enhanced greenhouse, or carbon dioxide utilization. For example, the captured carbon dioxide production step may be conducted in or near a location with calcium carbonate or limestone feedstock. For example, the captured carbon dioxide production step may be conducted in or near a system which absorbs carbon dioxide from one or more sources of carbon dioxide, which may include, but is not limited to, air, and may absorb and/or convert said carbon dioxide into calcium carbonate. For example, the calcining step may be conducted in a location with access to a relatively inexpensive fuel, such as flare gas, sour gas, natural gas, or sulfurous fuels, or coal, or biomass, or biofuel, or hydrogen, or nuclear, or geothermal, or waste heat, or heat, or a combination thereof. For example, the calcining step may be conducted in a location with or near demand for the calcined products, which may include, but are not limited to, calcium oxide, calcium hydroxide, magnesium oxide, magnesium hydroxide, cement, sulfur dioxide, nitrogen oxide, or a combination thereof. For example, the acid gas recovery step may be co-located with locations with waste cold. For example, the acid gas recovery step may be co-located with a LNG gasification facility, where, for example, the cooling provided by the phase change of LNG to natural gas may facilitate the separation or recovery of sulfur dioxide or other acid gas.

Example embodiments wherein one or more or a combination of steps are conducted in separate locations may comprise, including, but not limited to:

-   -   For example, the carbon dioxide generation step may comprise         multiple mixers or reactors, which may each be co-located with         one or more or a group of applications consuming or using carbon         dioxide. The calcining step and/or acid gas recovery step may be         conducted in a centralized location.     -   For example, the carbon dioxide generation step may comprise         multiple mixers or reactors, which may each be co-located with         one or more or a group of oil wells requiring carbon dioxide         enhanced oil recovery. The calcining step and/or acid gas         recovery step may be conducted in a centralized location.         Calcium carbonate may be supplied to the carbon dioxide         generation step from one or more or a combination of sources,         which may include, but is not limited to, mined calcium         carbonate, limestone, carbon dioxide air capture, or other         calcium carbonate source. Materials may be transferred between         process steps. For example, calcium sulfite may be transferred         from the carbon dioxide generation step to the calcining step,         which may comprise air-tight transport, railcars, trucks,         conveyor belt, or ship. For example, recovered sulfur dioxide         may be transferred from the acid gas recovery step to the carbon         dioxide generation step, which may comprise pipelines, air-tight         transport, railcars, tank trucks, trucks, or ship. For example,         SO2-rich solution and SO2-lean solution may be transferred         between the acid gas recovery step and the carbon dioxide         generation step.

If one or more steps are conducted in separate locations, one or more materials may be transferred between said separate locations.

One or more or a combination of steps of the present invention may be modular or transportable or a combination thereof. For example, the carbon dioxide generation step may comprise mobile reactors and/or other mobile or containerized structures. For example, the carbon dioxide generation step may be transported to a location requiring carbon dioxide. For example, if the location requiring carbon dioxide no longer needs carbon dioxide from the carbon dioxide generation step, said carbon dioxide generation step may be transported to a different location. For example, the calcination step and/or acid gas recovery step may comprise mobile calciners, or mobile absorption columns, or mobile separators, or other mobile or containerized structures, or a combination thereof. For example, the calcining step may be transported to locations with significant available low cost energy or an anticipated or temporary release of low cost energy, which may include, but is not limited to, natural gas releases, flare gas, sour gas, forest fire, geothermal events, lava, waste heat, or a combination thereof.

One or more or a combination of materials, reagents, products, inputs, outputs, or intermediates may be sourced, or used, or otherwise employed differently than described herein.

-   -   For example, calcium sulfite may comprise a byproduct or salable         product, and may comprise an output of the present invention.     -   For example, sulfur dioxide may comprise a virgin material         input, rather than or in addition to a regenerated intermediate.     -   For example, sulfur dioxide may be converted into elemental         sulfur using, for example, the Claus process.     -   For example, sulfur dioxide may be converted into sulfuric acid.     -   For example, sulfur dioxide or sulfur or a combination thereof         may be transported to the carbon dioxide generation step.     -   For example, virgin sulfur dioxide or virgin sulfur or virgin         hydrogen sulfide or a combination thereof may be transported to         the carbon dioxide generation step and/or directly added to the         carbon dioxide generation step. Virgin sulfur dioxide may be         added to the carbon dioxide generation step or may be dissolved         into a solution before said solution is added to the carbon         dioxide generation step or a combination thereof. Virgin sulfur         or virgin hydrogen sulfide may be combusted to produce virgin         sulfur dioxide. Virgin sulfur dioxide may be employed to makeup         for sulfur dioxide losses (which may also be referred to as         sulfur losses) in the process. Sulfur dioxide losses may         include, but are not limited to, sulfur dioxide consumed or         absorbed during the calcining step, or residual sulfur dioxide         in flue gases following one or more treatment steps, or residual         sulfur dioxide in flue gases which may be uneconomical to fully         regenerate, or sulfur dioxide converted to one or more other         compounds which may not be economically regenerable, sulfur         dioxide converted to one or more products, or a combination         thereof.

Some embodiments of the present invention may be constructed or implemented by retrofitting a pre-existing calciner for cement production and/or calcium oxide production to operate with input comprising calcium sulfite, rather than, or in addition to, calcium carbonate or limestone.

-   -   Some pre-existing calciners comprise materials compatible with         CaSO3 and/or SO2 and/or other regenerable acid gas or         regenerable acid gas salt. Some pre-existing calciners may         require one or more or a combination of components to be         replaced or coated to ensure material compatibility with CaSO3         and/or SO2.     -   Some pre-existing calciners may be retrofitted with systems or         materials to ensure lower diatomic oxygen concentration in the         calciner or in the input feeder or in the pulverizer or a         combination thereof.     -   A richer fuel to air ratio may be employed minimize diatomic         oxygen concentration or amounts in the calciner. Due to a richer         fuel mixture, some embodiments may require systems for removing         or eliminating or converting incomplete combustion products (for         example: carbon monoxide (CO) and VOCs). Said systems for         removing or eliminating incomplete combustion products may         include, but are not limited to, systems for further oxidizing         the incomplete combustion products, catalytic converters, or         systems for creating valuable products or chemicals or fuels         from incomplete combustion products.     -   Some pre-existing calciners may be retrofitted with systems or         materials to minimize the amount of air or other gases         comprising diatomic oxygen enter the calciner. For example,         improved seals and/or improved flow control may be implemented.     -   The fuel combustion step or system may be modified or replaced         to enable combustion of carbonaceous fuel, and/or sulfurous         fuel, and/or nitrogenous fuel and/or hydrogen fuel. For example,         the fuel combustion system may modified or replaced to enable         one or more combustion steps. For example, the fuel combustion         step or system may modified or replaced to enable one or more         combustion steps, wherein each combustion step may decrease the         concentration or amount of diatomic oxygen.     -   The carbon dioxide generation step, the acid gas recovery step,         other process elements, or a combination thereof may be added or         installed in a retrofit system.

The present invention may comprise a gas separation technology. For example, the present invention may be employed to regenerate an oxide with affinity for carbon dioxide from carbon dioxide salt. For example, the present invention may be employed to regenerate an oxide with affinity for carbon dioxide from carbon dioxide salt as part of a system for capturing CO2 from air or water or other potentially dilute CO2 stream. For example, the present invention may be employed to regenerate an oxide with affinity for carbon dioxide from a carbon dioxide salt as part of a system for removing carbon dioxide from sodium carbonate or potassium carbonate or other alkali-carbonate. For example, the present invention may be employed to regenerate an alkaline-earth oxide with affinity for carbon dioxide from an alkaline-earth carbonate as part of a system for regenerating an alkali-metal oxide or carbonate from an alkali-metal carbonate, sesquicarbonate, or bicarbonate.

For example, in an example CO2 air capture embodiment:

-   -   1. CO2 may be absorbed from air or water into a CO2-Lean alkali         solution (for example: a solution comprising lithium or sodium         or potassium or ammonia or amine), forming a CO2-Rich alkali         solution. Said CO2-Lean alkali solution may comprise an alkali         oxide solution. Said CO2-Lean alkali solution may comprise a         carbonate solution. Said CO2-Rich alkali solution may comprise a         carbonate or sesquicarbonate or bicarbonate solution. Said         CO2-Rich alkali solution may comprise a greater concentration of         CO2 or greater molar ratio of CO2 to alkali than said CO2-Lean         alkali solution.     -   2. Said CO2-Rich alkali solution may be contacted with a         CO2-Lean alkaline-earth solid, which may result in the formation         of a CO2-Lean alkali solution and a CO2-Rich alkaline-earth         solid. Said CO2-Rich alkaline-earth solid may comprise         alkaline-earth carbonate. Said CO2-Lean alkaline-earth solid may         comprise alkaline-earth oxide. Said CO2-Rich alkaline-earth         solid may comprise a greater concentration of CO2 or greater         molar ratio of CO2 to alkali than said CO2-Lean alkaline-earth         solid. Said CO2-Lean alkali solution may be transferred to         step 1. Said CO2-Rich alkaline-earth solid may be transferred to         step 3.     -   3. Said CO2-Rich alkaline-earth solid may be converted into a         CO2-Lean alkaline-earth solid using one or more or a combination         of systems or methods described herein. Said CO2-Lean         alkaline-earth solid may be transferred to step 2.

The present invention may enable the capture of carbon dioxide from air or water with, including, but not limited to, one or more or a combination of the following:

-   -   Reagents comprising an alkali, or an alkaline-earth, or a         combination thereof     -   The generation of captured carbon dioxide comprising a high         purity of gaseous carbon dioxide     -   The generation of captured carbon dioxide comprising a low         concentration of water vapor or solvent vapor     -   The generation of captured carbon dioxide at a high pressure of         carbon dioxide     -   The generation of captured carbon dioxide at mild temperatures     -   The generation of captured carbon dioxide, wherein the         regeneration process is separate from the CO2 generation step         and may involve the regeneration of an acid gas other than CO2.     -   Fuel in the process may be combusted in air and/or heat         transferred into the thermal regeneration or thermal         decomposition step comprises hot combustion gases     -   A CO2 air capture technology involving calcination without the         need for an air separation unit or an oxy-combustion unit or a         CO2 atmosphere calcination environment     -   The generation of captured carbon dioxide without the need for         an air separation unit or an oxy-combustion unit

Example Exemplary Embodiments and Sub-Embodiments

Example Exemplary Embodiments:

A process for producing captured carbon dioxide comprising:

Reacting a carbonate salt with a regenerable acid gas to produce a cation-regenerable acid gas salt and gaseous carbon dioxide;

Thermally decomposing said cation-regenerable acid gas salt to produce cement, an oxide, or a combination thereof

A process for producing captured carbon dioxide comprising:

Reacting a carbonate salt with a regenerable acid gas to produce a cation-regenerable acid gas salt and gaseous carbon dioxide;

Thermally decomposing said cation-regenerable acid gas salt to produce cement, an oxide, regenerable acid gas, or a combination thereof

A process for producing captured carbon dioxide comprising:

Reacting a carbonate salt with sulfur dioxide to produce a sulfite salt and gaseous carbon dioxide;

Thermally decomposing said sulfite salt to produce cement, an oxide, or a combination thereof

A process for producing captured carbon dioxide comprising:

Reacting a carbonate salt with sulfur dioxide-rich aqueous solution to produce a sulfite salt, gaseous carbon dioxide, and sulfur dioxide-lean aqueous solution;

Separating said sulfite salt from said sulfur dioxide-lean aqueous solution;

Thermally decomposing said separated sulfite salt to produce cement, an oxide, or a combination thereof

A process for producing cement or calcium oxide or CO2-lean alkaline earth carbonate and captured carbon dioxide comprising:

Reacting solid calcium carbonate with sulfur dioxide-rich aqueous solution to produce calcium sulfite, gaseous carbon dioxide, and sulfur dioxide-lean aqueous solution;

Separating said solid calcium sulfite from said sulfur dioxide-lean aqueous solution;

Thermally decomposing said separated calcium sulfite to produce calcium oxide, cement, or a combination thereof

A process for producing captured carbon dioxide comprising:

Reacting solid magnesium carbonate with sulfur dioxide-rich aqueous solution to produce magnesium sulfite, gaseous carbon dioxide, and sulfur dioxide-lean aqueous solution;

Separating said solid magnesium sulfite from said sulfur dioxide-lean aqueous solution;

Thermally decomposing said separated magnesium sulfite to produce gaseous sulfur dioxide

Example Exemplary Embodiments:

-   -   1. A process for producing captured carbon dioxide comprising:         Reacting solid calcium carbonate with sulfur dioxide-rich         solution to produce calcium sulfite, gaseous carbon dioxide, and         sulfur dioxide-lean solution; Separating said solid calcium         sulfite from said sulfur dioxide-lean solution; Thermally         decomposing said separated calcium sulfite to produce gaseous         sulfur dioxide     -   2. The process of exemplary embodiment 1 wherein said calcium         sulfite is thermally decomposed to produce cement     -   3. The process of exemplary embodiment 1 wherein said calcium         sulfite is thermally decomposed to produce calcium oxide     -   4. The process of exemplary embodiment 1 wherein said calcium         sulfite is thermally decomposed in a mixture with calcium         carbonate     -   5. The process of exemplary embodiment 1 wherein said calcium         sulfite is thermally decomposed in a mixture comprising clay, or         silicon dioxide, or aluminum oxide, or iron oxide, or iron         carbonate, or magnesium carbonate, or magnesium oxide, or         silicates, or aluminates, or shale, or sand, or fly ash, or ash,         or slag, or sulfur oxides, or a combination thereof     -   6. The process of exemplary embodiment 1 wherein said calcium         sulfite is thermally decomposed in a low oxygen environment     -   7. The process of exemplary embodiment 6 wherein said low oxygen         environment comprises a concentration of gaseous diatomic oxygen         of less than 20,000 PPM     -   8. The process of exemplary embodiment 6 wherein said low oxygen         environment comprises a concentration of gaseous diatomic oxygen         of less than 10,000 PPM     -   9. The process of exemplary embodiment 1 wherein said thermal         decomposition is conducted in the presence of hot gases     -   10. The process of exemplary embodiment 9 wherein said hot gases         comprise combustion gases     -   11. The process of exemplary embodiment 10 wherein said         combustion gases originated from the combustion of a fuel-rich         mixture     -   12. The process of exemplary embodiment 10 wherein said         combustion gases originated from the combustion of fuel         comprising carbonaceous fuel, sulfurous fuel, nitrogenous fuel,         hydrogen fuel, or a combination thereof     -   13. The process of exemplary embodiment 10 wherein said         combustion gases originated from a combustion process comprising         a first combustion step and a second combustion step;         -   Wherein the first combustion step comprises combusting             carbonaceous fuel; and         -   Wherein the second combustion step comprises combusting             sulfurous fuel     -   14. The process of exemplary embodiment 13 wherein the second         combustion step reduces the diatomic oxygen concentration     -   15. The process of exemplary embodiment 13 wherein the second         combustion step provides makeup sulfur dioxide to makeup for         sulfur dioxide losses in the process     -   16. The process of exemplary embodiment 10 wherein said         combustion gases originated from a combustion process comprising         a first combustion step and a second combustion step;         -   Wherein the first combustion step comprises combusting             carbonaceous fuel; and         -   Wherein the second combustion step comprises combusting             hydrogen fuel     -   17. The process of exemplary embodiment 10 wherein said         combustion gases originated from a combustion process comprising         a first combustion step and a second combustion step;         -   Wherein the first combustion step comprises combusting             hydrogen fuel; and         -   Wherein the second combustion step comprises combusting             sulfurous fuel     -   18. The process of exemplary embodiment 10 wherein said         combustion gases originated from a combustion process comprising         a first combustion step and a second combustion step;         -   Wherein the first combustion step comprises combusting             carbonaceous fuel; and         -   Wherein the second combustion step comprises combusting             nitrogenous fuel     -   19. The process of exemplary embodiment 10 wherein said         combustion gases originated from a combustion process comprising         a first combustion step and a second combustion step;         -   Wherein the first combustion step comprises combusting             carbonaceous fuel; and         -   Wherein the second combustion step comprises combusting a             sulfurous fuel and a nitrogenous fuel     -   20. The process of exemplary embodiment 10 wherein said         combustion gases originated from a combustion process comprising         a first combustion step and a second combustion step;         -   Wherein the first combustion step comprises combusting             carbonaceous fuel; and         -   Wherein the second combustion step comprises combusting a             hydrogen fuel and a sulfurous fuel     -   21. The process of exemplary embodiment 13 wherein said first         combustion step comprises combustion in a diatomic oxygen-rich         gas and forming diatomic oxygen-lean gas; and         -   Said second combustion step comprises combustion in said             diatomic oxygen-lean gas and forming a diatomic             oxygen-ultra-lean gas     -   22. The process of exemplary embodiment 1 wherein the gaseous         sulfur dioxide resulting from said thermal decomposition         comprises a mixture of post-combustion gases and sulfur dioxide     -   23. The process of exemplary embodiment 1 further comprising         recovering or separating at least a portion of the gaseous         sulfur dioxide resulting from said thermal decomposition     -   24. The process of exemplary embodiment 23 where said recovering         or separating comprises absorbing sulfur dioxide in a water wash         or physical absorbent wash     -   25. The process of exemplary embodiment 23 where said recovering         or separating comprises condensing sulfur dioxide     -   26. The process of exemplary embodiment 1 further comprising         recovering or separating at least a portion of the gaseous         sulfur dioxide resulting from said thermal decomposition by         absorption into a sulfur dioxide-lean solution, producing a         sulfur dioxide-rich solution     -   27. The process of exemplary embodiment 23 wherein said sulfur         dioxide-rich solution comprises the sulfur dioxide-rich solution         reacted with calcium carbonate in example exemplary embodiment 1     -   28. The process of exemplary embodiment 1 wherein said calcium         carbonate comprises limestone

A process for producing captured or high purity CO2 and/or calcium oxide and/or cement and/or CO2-Lean Alkaline-Earth Carbonate comprising:

-   -   1) SO2(aq)+CO2-Salt□SO2-Salt+CO2(g) or acid gas+CO2-salt□acid         gas□Salt+CO2(g)     -   2) Regenerating at least portion of the SO2 in said SO2-salt         -   Wherein at least a portion of the SO2 regenerated in ‘2)’ is             employed as the input SO2 in ‘1)’         -   Wherein the salt resulting from the regeneration of SO2             (‘2’) comprises an oxide or oxide salt         -   Wherein the resulting from the regeneration of SO2 (‘2’)             comprises an oxide or oxide salt and the oxide salt is             employed in the production of cement         -   Wherein the salt resulting from the regeneration of SO2             (‘2’) comprises cement         -   Wherein a solid byproduct of ‘2)’ comprises cement         -   Wherein ‘2’ is conducted in the presence of one or more or a             combination of feedstocks employed in the production of             Portland Cement         -   Wherein ‘2’ is conducted in the presence of one or more or a             combination of clay, silicates, aluminum oxides, iron             oxides, silicon oxides, magnesium oxides, or gypsum, or             sulfites, or sulfates         -   Wherein the salt resulting from the regeneration of SO2             (‘2’) is employed to absorb carbon dioxide from one or more             or a combination of gas streams comprising at least a             portion CO2         -   Wherein said one or more gas streams comprising at least a             portion CO2 comprises air         -   Wherein said one or more gas streams comprising at least a             portion CO2 comprises flue gas, biogas, natural gas, . . .         -   Wherein the salt resulting from the regeneration of SO2             (‘2’) comprises lime         -   Wherein the salt resulting from the regeneration of SO2             (‘2’) comprises quicklime         -   Wherein the salt resulting from the regeneration of SO2             (‘2’) is hydrated or mixed with water to produce slacked             lime         -   Wherein the salt resulting from the regeneration of SO2             (‘2’) comprises a valuable byproduct comprising an oxide             salt         -   Wherein the salt resulting from the regeneration of SO2             (‘2’) comprises a feedstock for cement         -   Wherein the CO2-Salt comprises limestone         -   Wherein the CO2-Salt comprises             A Process for Producing Captured or High Purity CO2 and             Calcium Oxide Comprising:     -   1) 1) SO2(aq)+CO2-Salt→SO2-Salt+CO2(g) or acid gas+CO2-salt→acid         gas-Salt+CO2(g)     -   2) Regenerating at least portion of the SO2 in said SO2-salt is         regenerated     -   Wherein at least a portion of the SO2 regenerated in ‘2)’ is         employed as the input SO2 in ‘1)’     -   Wherein the salt resulting from the regeneration of SO2 (‘2’)         comprises an oxide or oxide salt

A Process for Producing Calcium Oxide Comprising:

-   -   Thermally decomposing calcium sulfite to produce calcium oxide         and sulfur dioxide     -   Wherein said thermally decomposing is conducted in a low         diatomic oxygen environment     -   Wherein said low diatomic oxygen environment is facilitated by         the combustion of at least a portion of sulfur or hydrogen         sulfide or a combination thereof

A Process for Producing Calcium Oxide Comprising:

-   -   Thermally decomposing calcium sulfite to produce calcium oxide         and sulfur dioxide     -   Wherein said thermally decomposing is conducted in a low oxygen         environment         -   Wherein said low oxygen environment is facilitated by the             combustion of at least a portion of sulfur or hydrogen             sulfide or a combination thereof         -   Wherein said low oxygen environment is facilitated by a high             concentration of fuel relative to air during combustion,             such as a ratio of fuel to air near or equal to or greater             than that required by stoichiometry         -   Wherein said low oxygen environment is facilitated by the             use of a recirculating carrier gas             Notes     -   Sulfur dioxide may be provided as an example regenerable acid         gas     -   Increasing Partial Pressure and/or Concentration and/or Volume %         Concentration:         -   Some embodiments may pressurize or compress a gas comprising             sulfur dioxide (for example: compressing or pressurizing gas             stream represented by ‘13’ or ‘14’ or ‘15’ in FIG. 1) before             or during absorption of sulfur dioxide (For example:             absorption represented by ‘16’ in FIG. 1). Increasing the             pressure of a gas stream comprising sulfur dioxide may             increase the partial pressure of sulfur dioxide. Sulfur             dioxide may be provides as an example regenerable acid gas.         -   Some embodiments may increase the concentration and/or             partial pressure and/or volume % concentration of sulfur             dioxide in a gas mixture (for example: increase the             concentration and/or partial pressure and/or volume %             concentration of a gas stream represented by ‘13’ or ‘14’ or             ‘15’ in FIG. 1) using a gas membrane. Membranes and             membrane-based systems for concentrating gases are known in             the art and may be employed to increase the concentration of             sulfur dioxide in a gas mixture.         -   Increasing the partial pressure of sulfur dioxide may             increase the solubility of sulfur dioxide in an absorption             solution. By increasing the solubility of sulfur dioxide,             the sulfur dioxide absorption solution may achieve a greater             dissolved sulfur dioxide concentration, or the sulfur             dioxide absorption column may be smaller, or the sulfur             dioxide absorption solution may possess a greater absorption             capacity, or the sulfur dioxide absorption system may             operate at a lower absorption solution flow rate, or the             sulfur dioxide absorption system may operate at a greater             absorption efficiency or absorption recovery rate, or a             combination thereof. It may be desirable for said             pressurization or compression to be conducted after cooling             a gas stream comprising sulfur dioxide.     -   Some embodiments may involve increasing the concentration of         dissolved acid gas in the aqueous phase or liquid phase or in a         solution. For example, some embodiments may involve increasing         the concentration of dissolved acid gas using a membrane-based         process. For example, some embodiments may involve increasing         the concentration of dissolved acid gas using electrodialysis.         For example, some embodiments may involve increasing the         concentration of dissolved acid gas using a size-based         separation method. For example, some embodiments may involve         increasing the concentration of dissolved acid gas using reverse         osmosis, forward osmosis, nanofiltration, ultrafiltration, or a         combination thereof.     -   A gas stream comprising sulfur dioxide may be cooled or further         cooled or chilled before one or more or a combination of         absorption or separation or removal steps.     -   In FIG. 3, arrows in each figure may indicate the current batch         stage in the batch or semi-batch sequence of each reactor. FIG.         3A-3C may show each batch stage in an example batch sequence.     -   If desired, heat may be recovered from an exothermic enthalpy of         reaction during the reaction between calcium carbonate and         sulfur dioxide. If desired, energy, such as mechanical energy,         may be recovered from the pressure of CO2 generated during, for         example, the reaction between calcium carbonate and sulfur         dioxide. Alternatively, or additionally, the heat generated may         facilitate the reaction or facilitate generation of CO2.     -   Some embodiments may involve the generation of relatively high         partial pressure or purity CO2 during the production of calcium         oxide via the displacement of CO2 using an acid gas and the         regeneration of said acid gas.     -   Some embodiments may employ a chemically reactive absorbent in         the absorption step, for, for example, capturing carbon dioxide.         A chemically reactive absorbent may be beneficial due to,         including, but not limited to, one or more or a combination of         the following: greater absorption kinetics, greater absorption         capacity, or the ability to achieve greater rejection rate with         a liquid-phase membrane-based separation process.     -   Some embodiments may employ physical absorbents as absorbents         for absorbing or separating acid gas, such as sulfur dioxide.         Said physical absorbents may comprise aqueous or non-aqueous         solutions. Said physical absorbents may possess beneficial         properties. For example, said beneficial properties may include,         but is not limited to, one or more or a combination of the         following: greater solubility of sulfur dioxide relative to         water, faster absorption kinetics of sulfur dioxide relative to         water, faster kinetics relative to water, lower freezing point         temperature relative to water, lower vapor pressure relative to         water, higher boiling point relative to water, lower viscosity         relative to water. Said physical absorbents may comprise aqueous         solutions or non-aqueous solutions. Said physical absorbents may         comprise physical absorbents employed for acid gas removal known         in the art, which may include, but are not limited to, propylene         carbonate, ethers of polyethylene glycol, glycol ethers,         glycols, or methanol, or a combination thereof.     -   Some embodiments may employ physical absorbents with beneficial         properties as absorbents for absorbing or separating acid gas,         such as sulfur dioxide. Some embodiments may employ acid-gas         rich solutions of physical absorbents in, for example, the         carbon dioxide generating step.         Additional Notes:     -   Embodiments may be modular or transportable:         -   Conduct the CO2 production step in a modular fashion—CaSO3             production from CaCO3 may be conducted in a solid-gas or             solid-liquid mixing module. The CO2 generated may be             employed directly in a nearby oil field or other nearby CO2             demand application. The resulting CaSO3 may be transported             in an air-tight/oxygen-free container to a calciner, which             may or may not be located nearby. This enables the CO2             generation step to be conducted directly next to the oil             field or other CO2 demand application and/or may             significantly reduce the need for CO2 pipelines.             -   Inputs—                 -   CaCO3—transported or mined on site, may be                     pulverized if desired                 -   SO2—regenerated in the calcining step (calcining                     step may or may not be located nearby). Makeup SO2                     may generated or supplied onsite to make-up for                     losses of SO2. SO2 may be transported in liquid form                     by truck or by pipeline or by other means.             -   Treatment/Transfer Steps—                 -   CO2 separation from residual SO2                 -   Creating an oxygen-free or low oxygen environment                     for CaSO3 output, especially during transport             -   Outputs—                 -   CaSO3—transported in a practically oxygen-free                     environment to the calciner, which may or may not be                     located on site or near the site. Calciner employed                     to calcine CaSO3 may be similar a calciner typically                     employed in CaCO3 calcining, or may be a retrofitted                     calciner which was formerly employed in calcining                     CaCO3 or calcining cement or may be designed for                     calcining CaSO3.                 -   CO2—CO2 is produced, which can be employed directly                     onsite for, for example, enhanced oil recovery or                     CO2 conversion or CO2 sequestration.     -   Retrofit Pre-Existing Calciners for CaO Production using CaSO3         Feedstock:         -   Pre-existing calciners may be compatible with CaSO3 and SO2.             If needed, some calciners may require some parts to be             retrofitted with coatings or new materials to ensure             compatibility with SO2         -   Richer fuel to air ratio may be employed minimize O2 in gas             stream.             -   This also means a method for removing or eliminating                 incomplete combustion products (for example: carbon                 monoxide (CO) and VOCs) may be required. This may                 include, but are not limited to, methods for further                 oxidizing the CO, catalytic converters, or methods for                 creating value from CO.             -   Alternatively, or additionally, sulfur and/or nitrogen                 based fuels may be included or added to, for example,                 minimize oxygen concentration in combustion gases and/or                 to provide makeup SO2 for SO2 losses.         -   Water wash or other method to recover SO2 from flue gas             stream. Waste heat may also be recovered before, during, or             after this step     -   Air Capture         -   Calcium Carbonate-Calcium oxide is a core component of many             air capture technologies.         -   The present invention may be employed to regenerate calcium             carbonate into calcium oxide and produce high purity and/or             high-pressure CO2. Advantageously, in the present invention,             pure CO2 may be generated at a high pressure at room             temperature or relatively low pressures.         -   The present invention may comprise the CaO regeneration step             of a CO2 air capture or CO2 capture system, which may             include the production of high purity or high pressure CO2.     -   Generated CO2 may contain residual SO2. SO2 may be recovered or         separated by, for example, cooling and/or compression, which may         result in the liquification or condensation of the SO2.     -   Trace concentrations of SO2 may be recovered using a caustic         solution which may possess less affinity to react with CO2, for         example, which may include, but are not limited to, sodium         bicarbonate, sodium sulfite solution (which may convert into         bisulfite upon reaction with SO2), calcium carbonate, potassium         bicarbonate, bicarbonate salts, carbonate salts, sulfite salts,         metabisulfite salts, or a combination thereof.     -   Using a conventional calciner with a fuel rich environment to         prevent or minimize the presence of O2     -   Using the technique for thermal decomposition in an air-free         environment to create pure gaseous SO2     -   Waste heat

$\left. {{{CaCO}_{3}(s)} + {{SO}_{2}(g)}}\rightarrow{{{CaSO}_{3}(s)} + {{{CO}_{2}(g)}\left( {{- 49.37}\frac{kJ}{mol}} \right)}} \right.$

-   -   More general description of CaO production process/CO2         desorption process:         -   Acid gas is added to CaCO3 to form concentrated/pure/high             pressure CO2 and a Calcium-Acid Gas salt. Said Calcium-Acid             Gas salt is then decomposed or regenerated. Said             decomposition may involve forming Calcium Oxide and Acid             Gas. It may be desirable for the acid gas to comprise an             acid gas which can more easily be separated or recovered             from a gas mixture than CO2 and/or may be thermodynamically             favorable to react with CaCO3 to form CO2(g) and             Calcium-Acid Gas salt. For example, concentrated SO2 can             more easily be separated from a gas stream than concentrated             CO2 because it is highly soluble in water.     -   Use pulverized or highly crushed or high surface area or fine         particulate Calcium Carbonate as the input feedstock or         conversion into this small particulate calcium carbonate before         or during the reaction with SO2     -   CaCO3, CaSO3, or a combination thereof may also be pulverized or         mixed     -   Because the reaction of CaCO3 and SO2 is exothermic, the         reaction may require cooling or heat may be recovered from the         reaction.     -   SO2 may be reacted with CaCO3 as liquid SO2 or as SO2 dissolved         in water, or SO2 dissolved in another liquid or as gaseous SO2         or a combination thereof.     -   If SO2 is dissolved in water or another liquid, it may be         desirable for said liquid to have a relatively low concentration         of oxygen to prevent the oxidation of SO2 or oxidation of         resulting sulfite compounds.     -   It may be advantageous for SO2 to be dissolved in another         liquid, such as water, due to, for example, including, but not         limited to, one or more or a combination of the following:         -   To enhance reaction rate due to SO2 forming acids in             solvents (for example: sulfurous acid in water)         -   Enable a lower SO2 vapor pressure compared to gaseous or             liquid SO2, which may enable, for example, including, but             not limited to, one or more or a combination of the             following:             -   Reducing concentration and/or amount of SO2 in the                 desorbed CO2 (from the reaction of SO2 with CaCO3). This                 may reduce the energy requirements, OPEX, and CAPEX of                 systems required to separate residual SO2 from the CO2.             -   Enable higher temperature operation, which may enable,                 for example, including, but not limited to, one or more                 or a combination of the following:                 -   Faster reaction kinetics, which generally occurs at                     higher temperatures                 -   Lower cooling requirements, which may reduce, for                     example, CAPEX and/or OPEX                 -   Facilitate recovery of heat generated (e.g. waste                     heat). Water or other liquid solvent may be an                     effective heat transfer fluid and enable recovery of                     heat for use in other applications or within the                     process or may enable more effective cooling                 -   Depending on the temperature of the reaction, water                     or other solvent which SO2 is dissolved in may                     evaporate or boil. Solvent phase transition may                     facilitate internal cooling. Additionally, the                     solvent vapor may facilitate the recovery of SO2                     after CO2 desorption. For example, the solvent vapor                     may be condensed in a condenser, and SO2 may                     dissolve in said condensed solvent, reducing the SO2                     content in the CO2 before further treatment or                     compression of CO2                 -   Less energy required in recovering the SO2. SO2 may                     be recovered as an aqueous solution of SO2. The SO2                     rich solution after SO2 absorption may be further                     concentrated. Alternatively, the SO2 rich solution                     may be reacted with the CaCO3 without further                     concentrating of the SO2.                 -   Enable near ambient temperature or standard                     temperature operation, which may be considered                     higher or elevated temperature relative to the                     temperature of operation using liquid SO2 at                     standard pressures                 -    SO2 may have a lower vapor pressure in an aqueous                     solution or other solvent solution than as liquid                     SO2 at the same temperature.                 -    A process operating at near ambient temperature or                     standard environment temperature ranges may be                     cooled using low energy cooling sources, which may                     include, but are not limited to, one or more or a                     combination of the following: air cooled (e.g. heat                     exchanged with ambient air), water cooled, liquid                     cooled, evaporative water cooling, cooling tower                     cooling, radiative cooling, or cooling with a                     refrigeration cycle with a high coefficient of                     performance                 -    Cooling may be facilitated as liquid solution                     carrying SO2 may be heat exchanged with heat sink                     and CaCO3 (or calcium containing reaction                     intermediates or products). This may enable, for                     example, greater heat transfer, heat transfer to a                     greater amount calcium salt mass, or smaller vessel                     or a combination thereof, if compared to cooling                     using Solid-Solid heat transfer. It is important to                     note that Solid-Solid heat transfer may be employed                     if desired.     -   It may be advantageous for SO2 to be reacted in a relatively         pure form, such as liquid SO2, due to, for example, including,         but not limited to, one or more or a combination of the         following:         -   Faster reaction kinetics         -   Potentially higher enthalpy of reaction relative to aqueous             SO2         -   No or minimal water vapor in desorbed CO2         -   Sub-zero degrees Celsius temperature operation is possible         -   Lower total liquid volume or mass transfer         -   Higher pressure desorption         -   All or almost all SO2 entering reactor may react to form             CO2, which may enable, for example, including, but not             limited to, one or more or a combination of the following:             -   Residual SO2 in reactor may be minimal, especially if                 the CO2 desorption step operates in a batch or                 semi-batch configuration             -   High pressure CO2 desorbed at a low temperature             -   Desorbed CO2 will not dissolve in water, because there                 is no liquid water to dissolve in. For comparison, in a                 process employing water (or other solvent) other than                 SO2, water or solvent exiting the process may contain                 dissolved CO2 (especially if CO2 desorbs at a higher                 pressure or lower temperature), which may result in CO2                 losses.         -   If cooling the reactor is required, cooling may involve heat             exchange directly with liquid SO2 or cooling the vessel or             reactor using, for example, a liquid cooled or liquid-gas             phase transition cooled jacket or direct SO2 refrigerant             gas-liquid phase transition.     -   Sulfur dioxide may be separated from flue gas using condensing         or cooling separation or cryogenic separation. For example, flue         gas comprising sulfur dioxide may be cooled to at or below a dew         point or condensation temperature wherein at least a portion of         the sulfur dioxide condenses into a liquid phase.     -   Reactor may undergo mixing to facilitate, for example, the         SO2+CaCO3 reaction.     -   Process may be configured as batch, semi-batch, or continuous,         or a combination thereof.     -   SO2 losses may occur during operation. SO2 make-up may be         accomplished using, including, but not limited to, one or more         or a combination of methods.         -   For example, SO2 may be directly added to the liquid SO2             input source employed in the reaction of SO2 with CaCO3.         -   For example, elemental sulfur or hydrogen sulfide (for             example: hydrogen sulfide in sour natural gas) may be             combusted along with carbonaceous fuels. For example, sulfur             may be mixed with the coal or other fuel source employed to             power the calciner, which may result in the formation of             SO2(g). For example, sulfur may be burned as a separate fuel             input from carbonaceous fuels, which may involve burning             sulfur in a subsequent step. Elemental sulfur may be less             expensive and/or easier to transport than SO2. At least a             portion of the SO2 generated may be recovered and integrated             into the SO2 employed in the process by, for example, the             same methods or systems employed to recover the non-virgin             SO2. The SO2 generated by this method may mix with the SO2             generated in the calciner, which may enable seamless             integration of make-up SO2.         -   For example, elemental sulfur or hydrogen sulfide may be             burned after the burning of the conventional fuel (such as             coal or natural gas). This may have multiple benefits:             -   Reduce the concentration of residual O2 in the flue gas                 stream produced after the burning of conventional fuels                 (such as coal or natural gas).                 -   Incomplete combustion of the sulfur fuels may not be                     as significant or may be less likely as incomplete                     combustion of carbon-based fuels. Sulfur monoxide                     (SO) has a positive enthalpy of formation, while                     carbon monoxide (CO) has a strongly negative                     enthalpy of formation, so incomplete combustion in a                     low oxygen environment is much more favorable for a                     carbon-based fuel than a sulfur-based fuel or                     elemental sulfur.                 -   Enables the combustion of carbon-based fuels in a                     sufficiently oxygenated environment, allowing for                     optimal/efficient combustion, potentially minimizing                     OPEX and/or CAPEX                 -   Low oxygen or ultra-low oxygen concentration in the                     calciner, preventing oxidation of sulfite salts to                     sulfate salts             -   Produces SO2, which may comprise a portion or all of the                 makeup SO2, which may make-up for any SO2 losses during                 the process                 -   Note: SO2 produced during the combustion of                     sulfurous fuels to remove residual oxygen may exceed                     the SO2 losses/required makeup SO2. Excess SO2 may                     be employed in other value creating applications.                     For example, said other value creating applications                     may involve, including, but not limited to, one or                     more or a combination of the following: excess SO2                     may be sold or converted into sulfuric acid and                     sold, or converted into sulfite salts and sold, or                     reacted with H2S to produce elemental sulfur, or                     employed in a Claus process.                 -    The conversion of excess SO2 into sulfuric acid, if                     conducted, is an exothermic process. The heat                     generated from this reaction may be employed to                     power or supplement the energy load of other steps                     in the present invention or other applications                     demanding heat.     -   Residual SO2 may be further recovered using a regenerable amine         or other regenerable scrubbing process. It may be desirable for         said regenerable scrubbing process to minimally react with CO2         or less favorably react with CO2 or not react with CO2, relative         to SO2, as CO2 is may be in the gas stream with the SO2.         Alternatively or additionally, if the fuels employed to power         calcination are not carbon based (for example, may include, but         is not limited to, one or more or a combination of the         following: Hydrogen sulfide, sulfur, hydrogen, or ammonia), the         method employed for scrubbing SO2 may also favorably react with         CO2, however, due to the lack of or minimal presence of CO2, the         solvent may absorb SO2 with minimal CO2.     -   Scrubbing systems for recovering residual SO2 may be similar to         or the same as methods currently employed at calciners and power         plants. For example, for removal of PPT or PPM levels of SO2, a         sodium bicarbonate or sodium carbon solution may be employed or         calcium carbonate may be employed. If the present invention is         retrofitted into a pre-existing calciner, the pre-existing         calciner may already have a SO2 scrubber or related emissions         control technology.     -   CaCO3→CaSO3 conversion may not be 100%. Residual CaCO3 may be in         the calciner. As a result, it may be desirable to operate the         calciner at a temperature equal to or greater than the         temperature of typical CaCO3 calcining to ensure complete or         nearly complete conversion into CaO     -   Water wash may employ methods to separate ash and/or other         potential particulate matter from the wash solution before,         during, or after, for example, regenerating SO2.     -   Sodium sulfite or sodium bisulfite or calcium sulfite or other         sulfites or calcium sulfate or sulfates may be byproducts of the         process for scrubbing residual SO2     -   Residual SO2 mixed with desorbed CO2 from, for example, the         SO2+CaCO3 reaction, may be recovered using CaCO3 (for example: a         fluidized bed of CaCO3), which may react to form CaSO3.         Resulting CaSO3 may be used, for example, internally within the         present invention.     -   At least a SO2 in flue gas, which may be residual SO2, may be         recovered by reaction with CaCO3, which may result in CaSO3.         Said CaSO3 may be calcined to produce CaO.     -   At least a SO2 in flue gas, which may be residual SO2, may be         recovered by reaction with sodium or potassium bicarbonates or         carbonates, which may result in sodium or potassium sulfites or         bisulfites, or metabisulfites. Said sodium or potassium sulfites         or bisulfites, or metabisulfites may be regenerated into sodium         or potassium bicarbonates or carbonates by reacting with CaCO3         to produce CaSO3. Said CaSO3 may be calcined to produce CaO.     -   SO2 recovery method may involve, for example, concentrating SO2         or producing nearly pure SO2 after SO2 absorption     -   Bulk SO2 recovery may involve a water wash. The SO2-rich liquid         resulting from the water wash may undergo treatment to remove         solids and/or may be employed as the SO2 carrier entering a         SO2+CaCO3 reactor. Depending on the reaction kinetics of the         SO2-rich solution with the CaCO3, the concentration of SO2 in         the SO2-rich solution may be sufficient for the SO2 reaction         with CaCO3. Advantageously, employing the SO2-rich solution as         the SO2 carrier in the reaction of CaCO3 with SO2 may enable         lower CAPEX and OPEX, as it may eliminate the need for the         energy consumption (OPEX) and construction (CAPEX) of a SO2         concentrating step. Alternatively, or additionally, a SO2         concentrating step may be employed.     -   Adsorption CO2 capture process employing aqueous SO2 to desorb         CO2         Notes:

Some embodiments thermally decompose CaSO3 using combustion gases with complete combustion acting as, for example, heat source and stripping gas.

-   -   Complete combustion, or stoichiometric combustion, or combustion         with excess fuel, or combustion with all or almost all oxygen         present converted into combustion byproducts, or a combination         thereof may enable the combustion gases to be employed directly         as heat carriers because the gases may lack oxygen. The lack of         oxygen or very low concentrations of oxygen may enable CaSO3 to         be decomposed without oxidizing the sulfur species, preventing         the formation of SO3(g) or CaSO4.     -   Combustion gases may be pumped or otherwise forced into contact         with the CaSO3 in the one or more CaSO3 decomposition or         desorption reactors     -   Combustion gases may be produced by the combustion of         carbon-based fuels or fuels without carbon or a combination         thereof         -   For carbon based fuels, it may be desirable for the reactor             temperature during at least one portion of the thermal             decomposition to exceed the decomposition temperature of             calcium carbonate. This may prevent a reaction of CO2 with             calcium oxide or hydroxide, which may prevent the formation             of calcium carbonate. This may also enable any residual             calcium carbonate in the reactor to be thermally decomposed,             which may enable higher conversion efficiency to calcium             oxide.     -   It may be desirable to employ non-carbon based fuels, which may         include, but are not limited to, H2, NH3, H2S, or a combination         thereof.         -   Non-carbon based fuels may be desirable as they may not             produce CO2, which may enable the use of lower temperatures             during decomposition as there may be no need to inhibit             calcium carbonate formation if there is no CO2 present.             -   For example, H2 may produce steam, which may not react                 with CaO at the decomposition temperature of CaSO3.             -   NH3 may produce NO2, which may not react with CaO at the                 decomposition temperature of CaSO3. Although, NO2 may                 react with CaO, CaSO3, or CaCO3 at lower temperatures,                 which may or may not be desirable.             -   H2S may produce SO2, which is the same gas as the                 decomposition product of CaSO3. This may be beneficial,                 as a higher concentration of SO2 may be generated and it                 may enable a simple composition of the gas stream                 leaving the decomposition reactor.                 Additional Description

The present invention converts CaCO3 into CO2 and CaO. In the process, both CO2 and CaO may be valuable byproducts. The present invention may produce high purity and/or high pressure CO2, which may be suitable for use in enhanced oil recovery and other CO2 utilization or conversion applications. CaO produced by the present invention may be suitable for, for example, including, but not limited to, the production of cement or may comprise quicklime or may be employed to capture CO2 from the air or a combination thereof.

CaO is currently produced by heating CaCO3 or limestone to decompose it into CaO and CO2 in a process called calcining. Calcining is energy intensive and CO2 emission intensive. The process of calcining produces CO2 in the form of flue gas. For CO2 to be useful from calcining, the CO2 must be separated from the flue gas by a post-combustion CO2 capture system, which requires very high capital and operating costs, which generally exceed the value of said CO2. Alternatively, a calciner may be powered by fuel combusted in pure oxygen (oxy-combustion) from an air separation unit. Similar to post-combustion CO2 capture, Oxy-combustion has high capital and operating costs due to the operating costs and capital costs involved with the air separation unit and the significantly higher operating temperature required for decomposing CaCO3 in pure CO2.

The present invention may react SO2 (gas or liquid or aqueous solution or non-aqueous solution or supercritical or solid or a combination thereof) with CaCO3, which may result in the formation of CaSO3 and CO2. The resulting CO2 may undergo further purification to remove at least a portion of SO2 or any other gases present from the CO2. CO2 may be sold or used for one or more applications of high pressure and/or purity CO2. CaSO3 may be thermally decomposed into CaO and SO3. The thermal decomposition of CaSO3 may involve an oxygen free or ultra-low oxygen environment. If a carrier gas is employed, SO3 may be separated from said carrier or stripping gas and may be recovered or regenerated for re-use internally. CaO may be sold or used for one or more applications of CaO. The process may be batch, semi-batch, semi-continuous, continuous, or a combination thereof.

Example Embodiment 1

-   1. CaCO3 may be placed in a vessel or container. After a desired     amount of CaCO3 is dded to said vessel or container, the container     may be closed. The container may be evacuated of most or all of the     remaining oxygen gas or air by, for example, including, but not     limited to, one or more or a combination of methods:     -   a. Employing a vacuum pump to evacuate air or O2 from the         container and reduce pressure to near vacuum     -   b. Purging with nitrogen or other purge gas     -   c. Introducing an amount of CH3, H2, Sulfur, H2S, or NH3 or         other combustible or oxygen absorbing reagent and combusting         these reagents to remove at least a portion of the O2     -   d. Gas separation membrane to separate at least a portion of O2         from the remaining gases     -   e. Employing an oxygen scavenger, such as, for example, iron         oxides or copper or copper oxides     -   f. Condensing a portion of the oxygen or condensing another gas         to facilitate the separation of oxygen -   2. CaCO3+SO2 ⇔CaSO3+CO2 -   3. CaSO3+Heat⇔CaO+SO2

Further Description of Step ‘2)’: SO2 may be injected into the container with CaCO3 as one or more or a combination of phases, although for the purposes of description of the present example embodiment, the SO2 may be injected into container with CaCO3 as SO2 liquid, SO2 aqueous, or SO2 non-aqueous solution or a combination thereof. It may be desirable for said liquid or solution to be de-aerated or contain an ultra-low concentration of oxygen. The SO2 may react with said CaCO3 to form CaSO3 and CO2. If desirable, the container/reactor may be heated or cooled or the temperature may be uncontrolled or the temperature may be controlled or a combination thereof. CO2(g) which may result from the reaction may contain a portion of residual SO2 vapor.

Advantageously, SO2 may be easily separated from CO2 due to its, for example, very different boiling point, or significantly higher solubility in water, or different molar mass, or ability to be removed by a SO2 scavenger, or a combination thereof. Residual SO2 in the CO2 may be separated by, for example, including, but not limited to, one or more or a combination of the following: condensation, cooling condensation, compression condensation, water wash, gas separation membrane, reactive absorption and stripping, or SO2 scrubbing molecule (for example: sodium carbonate, sodium bicarbonate, calcium carbonate, calcium bicarbonate, amine-carbon dioxide, water or ammonium carbonate). The resulting high purity CO2 may be employed in one or more applications for pure CO2, which may include, but are not limited to, enhanced oil recovery, CO2 sequestration, conversion into chemicals, or non-hydraulic cement production. Residual SO2 may be recovered or regenerated and/or reused within the process.

Further Description of Step ‘3)’: CaSO3 may be thermally decomposed. Desirable decomposition byproducts may comprise, for example, CaO and SO2. CaSO3 may be decomposed through heating at or above one or more decomposition temperatures. To maximize the formation of CaO and SO2 and/or minimize the formation of CaS or CaSO4, reaction temperature may be maintained between 600-680° C. or above 780° C. Per paper titled ‘The Thermal Decomposition Process of Calcium Sulfite’ by Royoko et al, CaSO3 may decompose into CaSO4 and CaS at a temperature between 680° C. and 780° C., and thus, it may be desirable to decompose Calcium Sulfite outside the 680° C.-780° C. temperature range if the objective is to form CaO and SO2.

Thermal input may be supplied by, for example, directly heating the container containing CaSO3 or heating a carrier gas which is passed over or through said CaSO3 or heating SO2 (which may also be employed as a carrier gas) or a combination thereof. The container may comprise one or more solid handling or solids storage containers which may be heated known in the art, which may include, but are not limited to, one or more or a combination of the following: rotary kiln, kiln, column, oven, mixing oven, or a combination thereof.

Carrier gas may comprise a non-reactive gas or a gas which is non-reactive with the reagents present under the conditions present (although may comprise a reactive gas if desired), which may include, but are not limited to, one or more or a combination of the following: nitrogen, argon, helium, fluorinated gases, CFCs, HFCs, or sulfur hexafluoride. If a non-SO2 carrier gas is employed, the SO2-lean carrier gas may be heated before or while entering the container containing CaSO3. SO2 may desorb into said carrier gas (which may also be called a stripping gas), which may form SO2-rich carrier gas and CaSO3 may be converted into CaO. Said SO2-rich carrier gas may exit the container containing CaSO3 or CaO or both. To reduce energy consumption, the SO2-rich carrier gas exiting said container containing CaSO3 or CaO or both may be heat exchanged in, for example, a cross heat exchanger, with incoming SO2-lean carrier gas. Following the cross exchanger, at least a portion of the SO2 in said SO2-rich carrier gas may be separated. SO2 separation may be conducted using one or more methods described herein or one or more methods known in the art, which may include, for example, a water wash or non-aqueous liquid wash or a combination thereof. If a water wash or non-aqueous liquid wash is employed, it may be desirable for the rich solution of SO2 resulting from said water wash or non-aqueous liquid wash or both to comprise the medium for SO2 input for step 2, as, for example, this may eliminate or reduce the energy requirement for recovering SO2 by, for example, preventing the need to steam strip or desorb SO2 from said wash solutions. It may be desirable for the water or non-aqueous medium or both to be oxygen-free or contain low concentrations of oxygen. The remaining SO2-lean carrier gas may be recirculated.

Alternatively, the CaSO3 may be decomposed in a pure or concentrated SO2 environment. A pure SO2 environment may be advantageous because, for example, including, but not limited, one or more or a combination of the following: a) SO2 desorbed may be directly reused, minimizing or eliminating the need for additional processing steps, such water washing; or b) reduce heat exchange losses, as hot SO2 exiting may be directly heat exchanged with any SO2 entering the process or supplement heat input if, for example, no addition SO2 is entering; or c) reduce the total amount of mass requiring heating. A pure SO2 environment may have the disadvantage of potentially higher temperature requirements and/or enthalpy of desorption because the CaSO3 may be decomposed in a pure SO3 environment, which, according to the Le Chatelier Principle, may increase the temperature requirements and/or enthalpy of desorption relative to a lower SO2 concentration environment enabled by a carrier gas.

Advantageously, a non-SO2 carrier gas may be employed, while being able to recover the SO2. SO2, unlike CO2, may be condensable and highly water soluble, enabling separation of SO2 from carrier gas streams, which may be inert gas streams, at a relatively low cost.

Note: The present invention may employ other carbonate or bicarbonate salts as feedstocks, which may include, but are not limited to, sodium and potassium carbonates or bicarbonates.

Note: May employ materials compatible with one or more or a combination of the following: SO2, CO2, or H2O or one or more of the fuels (if any) employed in heating and/or their combustion products. It may be desirable for said materials to be compatible at temperature ranges which the materials will be operating

Note: Advantageous, the present invention does not require an air separation unit or post-combustion CO2 capture to produce pure CO2. Also advantageously, pure CO2 may be produced at a high pressure and/or relatively low temperature and/or with relatively low water vapor concentration.

Note: It may be desirable for the CaCO3 or SO2 or CaSO3 or CaO or a combination thereof in an oxygen-free or very low oxygen environment. An oxygen-free or very low oxygen environment may, for example, prevent the oxidation of SO2 or CaSO3 or other SO3 salt into a SO4 salt.

Note: The present invention may be employed to regenerate CaO from CaCO3 or similar carbonate or bicarbonate molecules in a CO2 capture process. For example, the present invention may be employed in a device to capture CO2 from the air.

Note: The SO2 may be substituted with nitric acid (HNO3). Ca(NO3)2 (which may be a resulting byproduct) can be thermally decomposed in a similar manner to CaSO3 to form CaO and NOx or O2 or NO2 or NO or a combination thereof. NOx, NO2, or NO may be converted back into nitric acid through reaction with water in, for example, the NOx+O2 and NOx+H2O reaction steps of the Ostwald process, regenerating the nitric acid in the present embodiment. Advantageously, Ca(NO3)2 does not oxidize in the presence of O2, which may enable the process to operate in an environment with the presence of O2, if desired.

Note: The carrier gas may comprise a reactive gas if desired. For example, steam may be employed as a carrier gas. Advantageously, steam may condense following calcination and the heat generated may be recoverable and the heat generated may exceed initial heat input to generate steam due to, for example, the exothermic dissolution of SO2 in the condensed steam (water) and/or the exothermic reaction of H2O with CaO to produce calcium hydroxide. It is important to note that calcium hydroxide may be a byproduct of this version of the present invention.

Note: Any excess water may be removed from system. Similarly, water may be added to the system if desired. Water removal may be conducted by for example, including, but not limited to, one or more or a combination of the following: forward osmosis, decanter, separatory funnel, coalescer, centrifuge, filter, switchable solvent, cyclone, semi-permeable membrane, nanofiltration, organic solvent nanofiltration, reverse osmosis, ultrafiltration, microfiltration, hot nanofiltration, hot ultrafiltration, distillation, membrane distillation, flash distillation, multi-effect distillation, mechanical vapor compression distillation, or hybrid systems.

Note: Sodium salts may be employed. Sodium Bicarbonate may be decomposed to form Sodium Carbonate, Sodium hydroxide, Sodium Sesquicarbonate, or a combination thereof, or other sodium-carbon dioxide or sodium bicarbonate derivative chemicals.

Note: Separation Devices may include, but are not limited to, one or more or a combination of the following: decanter, separatory funnel, coalescer, centrifuge, filter, switchable solvent, cyclone, semi-permeable membrane, nanofiltration, organic solvent nanofiltration, reverse osmosis, ultrafiltration, microfiltration, hot nanofiltration, hot ultrafiltration, distillation, membrane distillation, flash distillation, multi-effect distillation, mechanical vapor compression distillation, or hybrid systems

Note: Heat sources may include, but are not limited to, one or more or a combination of the following: flare gas heat, natural gas combustion, nuclear heat, Waste Heat, Ambient Temperature Changes, Diurnal Temperature Variation, Thermocline liquid body, thermocline solid body, thermocline gaseous body, Thermocline of a water body, halocline, heat pump, solar thermal, solar thermal pond, light, electricity, steam, combustion, compression, pressure increase, geothermal, radiative heat, condensation, exothermic dissolution, exothermic precipitation, exothermic formation of more liquid phases, exothermic formation of less liquid phases, exothermic phase change, or other heat sources described herein.

Note: Systems and methods described herein may be batch, semi-batch, or continuous, or a combination thereof.

Because CaCO3 and CaSO3 may be minimally soluble in water, the aqueous sulfur dioxide may only penetrate surface layers of the CaCO3, meaning some CaCO3 may not undergo the reaction due to a protective layer of the CaSO3. Increasing the reaction yield may be facilitated by, including, but not limited to, reducing CaCO3 particle size and/or maximizing CaCO3 surface area to mass/volume. Increasing the reaction yield may be conducted by adjusting mixing rate and contact time.

Additional Specific Embodiments

-   1. A process for producing captured carbon dioxide comprising:     reacting calcium carbonate with sulfur dioxide to produce calcium     sulfite and gaseous carbon dioxide; and thermally decomposing said     calcium sulfite to produce gaseous sulfur dioxide. -   2. The process of embodiment 1 wherein said thermal decomposing is     conducted under conditions to further produce cement. -   3. The process of embodiment 1 wherein said thermal decomposed is     conducted under conditions to further produce calcium oxide. -   4. The process of embodiment 1 wherein said thermal decomposing is     conducted in a mixture with calcium carbonate. -   5. The process of embodiment 1 wherein said thermal decomposing is     conducted in a mixture comprising a clay, or silicon dioxide, or     aluminum oxide, or iron oxide, or iron carbonate, or magnesium     carbonate, or magnesium oxide, or a silicate, or an aluminate, or     shale, or sand, or fly ash, or ash, or slag, or a sulfur oxide, or a     combination thereof. -   6. The process of embodiment 1 wherein said thermal decomposing is     conducted in a low oxygen environment. -   7. The process of embodiment 6 wherein said low oxygen environment     comprises a concentration of gaseous diatomic oxygen of less than     20,000 PPM. -   8. The process of embodiment 6 wherein said low oxygen environment     comprises a concentration of gaseous diatomic oxygen of less than     10,000 PPM. -   9. The process of embodiment 1 wherein said thermal decomposing is     conducted in the presence of at least one hot gas. -   10. The process of embodiment 9 wherein said at least one hot gas     comprises a combustion gas. -   11. The process of embodiment 10 wherein said combustion gas     originated from combustion of a fuel-rich mixture. -   12. The process of embodiment 10 wherein said combustion gas     originated from combustion of a fuel comprising a carbonaceous fuel,     or a sulfurous fuel, or a nitrogenous fuel, or a hydrogen fuel, or a     combination thereof. -   13. The process of embodiment 10 wherein said combustion gas     originated from a combustion process comprising a first combustion     step and a second combustion step; wherein the first combustion step     comprises combusting carbonaceous fuel; and wherein the second     combustion step comprises combusting sulfurous fuel. -   14. The process of embodiment 13 wherein the second combustion step     reduces diatomic oxygen concentration. -   15. The process of embodiment 13 wherein sulfur dioxide is provided     in the second combustion step to makeup for sulfur dioxide loss in     the process. -   16. The process of embodiment 10 wherein said combustion gas     originated from a combustion process comprising a first combustion     step and a second combustion step; wherein the first combustion step     comprises combusting carbonaceous fuel; and wherein the second     combustion step comprises combusting hydrogen fuel. -   17. The process of embodiment 10 wherein said combustion gas     originated from a combustion process comprising a first combustion     step and a second combustion step; wherein the first combustion step     comprises combusting hydrogen fuel; and wherein the second     combustion step comprises combusting sulfurous fuel -   18. The process of embodiment 10 wherein said combustion gas     originated from a combustion process comprising a first combustion     step and a second combustion step; wherein the first combustion step     comprises combusting carbonaceous fuel; and wherein the second     combustion step comprises combusting nitrogenous fuel. -   19. The process of embodiment 10 wherein said combustion gas     originated from a combustion process comprising a first combustion     step and a second combustion step; wherein the first combustion step     comprises combusting carbonaceous fuel; and wherein the second     combustion step comprises combusting a mixture comprising a     sulfurous fuel and a nitrogenous fuel. -   20. The process of embodiment 10 wherein said combustion gas     originated from a combustion process comprising a first combustion     step and a second combustion step; wherein the first combustion step     comprises combusting carbonaceous fuel; and wherein the second     combustion step comprises combusting a mixture comprising a hydrogen     fuel and a sulfurous fuel. -   21. The process of embodiment 13 wherein said first combustion step     comprises combusting the carbonaceous fuel with a diatomic     oxygen-rich gas to form a diatomic oxygen-lean gas; and wherein said     second combustion step comprises combusting the sulfurous fuel with     the diatomic oxygen-lean gas and to form a diatomic     oxygen-ultra-lean gas. -   22. The process of embodiment 1 wherein the gaseous sulfur dioxide     comprises a mixture of other gases -   23. The process of embodiment 1 further comprising recovering at     least a portion of the gaseous sulfur dioxide resulting from said     thermal decomposing. -   24. The process of embodiment 23 where said recovering comprises     absorbing sulfur dioxide in a wash. -   25. The process of embodiment 23 where said recovering comprises     condensing sulfur dioxide. -   26. The process of embodiment 1 further comprising recovering at     least a portion of the gaseous sulfur dioxide resulting from said     thermal decomposing by absorption of said gaseous sulfur dioxide     into a sulfur dioxide-lean solution to produce a sulfur dioxide-rich     solution. -   27. The process of embodiment 1 wherein the sulfur dioxide reacted     with the calcium carbonate is in the form of a sulfur dioxide-rich     solution and wherein the reaction with the calcium carbonate further     produces a sulfur dioxide-lean solution. -   28. The process of embodiment 27 which further comprises recovering     at least a portion of the gaseous sulfur dioxide resulting from said     thermal decomposing by absorption of said gaseous sulfur dioxide     into the sulfur dioxide-lean solution to produce a sulfur     dioxide-rich solution. -   29. The process of embodiment 1 wherein said calcium carbonate     comprises limestone.

A process for producing captured carbon dioxide comprising:

-   -   reacting a carbonate salt with a regenerable acid gas to produce         a cation-regenerable acid gas salt and gaseous carbon dioxide;         and     -   thermally decomposing said cation-regenerable acid gas salt to         produce cement, an oxide, or a combination thereof.

A process for producing captured carbon dioxide comprising:

-   -   reacting a carbonate salt with sulfur dioxide to produce a         sulfite salt and gaseous carbon dioxide; and     -   thermally decomposing said sulfite salt to produce cement, an         oxide, or a combination thereof.

A process for producing captured carbon dioxide comprising:

-   -   reacting a carbonate salt with sulfur dioxide-rich solution to         produce a sulfite salt, gaseous carbon dioxide, and sulfur         dioxide-lean solution;     -   separating said sulfite salt from said sulfur dioxide-lean         solution; and thermally decomposing said separated sulfite salt         to produce cement, an oxide, or a combination thereof.

A process for producing cement or calcium oxide and captured carbon dioxide comprising:

-   -   reacting solid calcium carbonate with sulfur dioxide-rich         solution to produce calcium sulfite, gaseous carbon dioxide, and         sulfur dioxide-lean solution;     -   separating said solid calcium sulfite from said sulfur         dioxide-lean solution; and thermally decomposing said separated         calcium sulfite to produce calcium oxide, cement, or a         combination thereof.

A process for producing captured carbon dioxide comprising:

-   -   reacting solid magnesium carbonate with sulfur dioxide-rich         solution to produce magnesium sulfite, gaseous carbon dioxide,         and sulfur dioxide-lean solution;     -   separating said solid magnesium sulfite from said sulfur         dioxide-lean solution; and thermally decomposing said separated         magnesium sulfite to produce gaseous sulfur dioxide.

Example Chemistry

-   -   (1) MgCa(CO₃)₂(s)+2SO₂(aq)→CaSO₃(s)+MgSO₃(aq)+2CO₂(g)     -   (2) Solid-Liquid Separation     -   (3) MgSO₃(aq) (dilute         feed)+Concentrating→MgSO₃(aq)(concentrate)+Water (permeate)     -   (4) MgSO₃(aq)(concentrate)+cooling→MgSO₃(s)+MgSO₃(aq)(remaining         solution)

Note: MgSO₃(aq)(remaining solution) may undergo further treatment to remove non-MgSO₃ reagents, or may be mixed with the reactants of ‘(3)’, or may be mixed with the reactants of ‘9’, or any combination thereof

-   -   (5) MgSO₃(s)+Drying→MgSO₃(s) (less wet, or less hydrated, or         anhydrous, or any combination thereof)     -   (6) MgSO₃(s)+Heat→MgO(s)+SO₂(g)     -   (7) CaSO₃(s)+Drying→CaSO₃(s) (less wet, or less hydrated, or         anhydrous, or any combination thereof)     -   (8) CaSO₃(s)+Heat→CaO(s)+SO₂(g)     -   (9) Water (permeate)+2SO₂(g)→2SO₂(aq)         Example Step-by-Step Description     -   (1) MgCa(CO₃)₂(s) is contacted with or reacted with a solution         comprising aqueous sulfur dioxide, which may result in the         formation of captured CO₂(g), or magnesium sulfite, or calcium         sulfite, or any combination thereof. Captured CO₂ may comprise         an output of the process and may undergo further treatment or         compression. Due to the dilute concentration of aqueous sulfur         dioxide, or the limited residence time of the ‘contacting’ or         ‘reacting’, or the stoichiometric molar ratio of sulfur dioxide         to calcium and/or magnesium, minimal ‘bisulfite’ may form,         and/or magnesium sulfite may be soluble, and/or calcium sulfite         may be insoluble. It is important to note magnesium sulfite is         soluble in water, while calcium sulfite is practically insoluble         in water. The aqueous solution may comprise aqueous magnesium         sulfite. The solid phase may comprise calcium sulfite, or         residual silicates, or other sulfites, or iron sulfite, or zinc         sulfite, or manganese sulfite, or any combination thereof. The         present step may be conducted at an elevated temperature, such         as a temperature greater than 20° C., or 30° C., or 40° C., or         50° C., or 60° C., or 70° C., or 80° C., or 90° C., to, for         example, facilitate reaction kinetics, or increase reaction         rate, or increase dissolution rate of MgSO₃. The solid-liquid         mixture may be transferred to step 2.     -   (2) The solid liquid mixture may undergo a solid-liquid separate         process, forming a solid phase comprising calcium sulfite, or         residual silicates, or other sulfites, or iron sulfite, or zinc         sulfite, or manganese sulfite, or any combination thereof and a         liquid phase comprising aqueous magnesium sulfite, which may         comprise ‘dilute aqueous magnesium sulfite’.     -   (3) Dilute aqueous magnesium sulfite may be concentrated using         reverse osmosis. It may be desirable to further heat or increase         the temperature of MgSO₃(aq) before or during concentrating of         MgSO₃(aq) using reverse osmosis to, for example, maximize the         solubility and/or maximize the concentration of MgSO₃(aq) in the         retentate or concentrate. At least a portion of the permeate         produced from the reverse osmosis process may be transferred to         and/or employed as a SO₂-lean absorption solution in an SO₂         absorption process or process for producing aqueous sulfur         dioxide. Said permeate may be heat exchanged with the aqueous         sulfurous acid entering step ‘(1)’ to recover heat and pre-cool         the permeate before an SO₂ absorption step. The retentate or         concentrate may be transferred to step ‘(4)’.     -   (4) A concentrate solution comprising aqueous magnesium sulfite         may be cooled to precipitate at least a portion of the MgSO₃         from the concentrate. MgSO₃(s) may be separated using a         solid-liquid separation and transferred to step ‘5’. The         remaining solution separated after MgSO₃(s) separation may         comprise remaining MgSO₃(aq). In some embodiments, at least a         portion of the remaining MgSO₃(aq) may be transferred to step         ‘(3)’ and/or mixed with the dilute aqueous magnesium sulfite         before or during reverse osmosis concentrating. In some         embodiments, at least a portion of the remaining MgSO₃(aq) may         be heated and further concentrated using a reverse osmosis         process, or a forward osmosis process, or a distillation         process, or cryodesalination process, or a freezing desalination         process, or crystalizing process, or a combination thereof         and/or MgSO₃(s) may be precipitated, or any combination thereof.         In some embodiments, at least a portion of the remaining         MgSO₃(aq) may be treated to remove at least a portion of         non-MgSO₃(aq) impurities. In some embodiments, at least a         portion of the remaining MgSO₃(aq) may be transferred to an SO₂         absorption step, such as step ‘9’, and/or mixed with water or         water permeate.     -   (5) MgSO₃(s) may be dried using one or more or a combination of         drying processes. For example, MgSO₃(s) may be heated in the         presence of a carrier gas and water may be removed from said         carrier gas. For example, MgSO₃(s) may be dried using the         hydration of calcium oxide to calcium hydroxide, the hydration         of magnesium oxide to magnesium hydroxide, or a combination         thereof. For example, MgSO₃(s) may be dried in the presence of a         dry carrier gas. For example, MgSO₃(s) may be dried in the         presence of a carrier gas, wherein said carrier gas comprises an         inert gas or a gas without or with minimal concentration of         diatomic oxygen. For example, MgSO₃(s) may be dried in multiple         stages. For example, a MgSO₃(s) hydrate may be melted into a         liquid solution and MgSO₃(s) upon heating and water may be         further separated using, for example, a zero liquid discharge         process. For example, MgSO₃(s) may be dehydrated in a         calcination process to produce magnesium oxide and sulfur         dioxide. It may be desirable to dry or dehydrate magnesium         sulfite before calcining to, for example, minimize energy         consumption, or minimize the energy consumption during         calcining, or minimize the cost of energy used in the process,         or a combination thereof.     -   (6) MgSO₃(s) may be transferred to a kiln or calcining process,         wherein MgSO₃(s) may be thermally decomposed into MgO(s) and         SO₂(g). Said MgO(s) may comprise a valuable byproduct and/or may         undergo further treatment. For example, said MgO(s) may be         hydrated to form Mg(OH)₂.     -   (7) Calcium sulfite (CaSO₃(s)) may be dried using one or more or         a combination of drying processes. For example, CaSO₃(s) may be         heated in the presence of a carrier gas and water may be removed         from said carrier gas. For example, CaSO₃(s) may be dried using         the hydration of calcium oxide to calcium hydroxide, the         hydration of magnesium oxide to magnesium hydroxide, or a         combination thereof. For example, CaSO₃(s) may be dried in the         presence of a dry carrier gas. For example, CaSO₃(s) may be         dried in the presence of a carrier gas, wherein said carrier gas         comprises an inert gas or a gas without or with minimal         concentration of diatomic oxygen. For example, CaSO₃(s) may be         dried in multiple stages. For example, a CaSO₃(s) hydrate may be         melted into a liquid solution and CaSO₃(s) upon heating and         water may be further separated using, for example, a zero liquid         discharge process. For example, CaSO₃(s) may be dehydrated in a         calcination process to produce calcium oxide and sulfur dioxide.         It may be desirable to dry or dehydrate calcium sulfite before         calcining to, for example, minimize energy consumption, or         minimize the energy consumption during calcining, or minimize         the cost of energy used in the process, or a combination         thereof.     -   (8) CaSO₃(s) may be transferred to a kiln or calcining process,         wherein CaSO₃(s) may be thermally decomposed into CaO(s) and         SO₂(g). Said CaO(s) may comprise a valuable byproduct and/or may         undergo further treatment. For example, said CaO(s) may be         hydrated to form Ca(OH)₂. For example, said CaO(s) may be         converted to precipitated calcium carbonate.     -   (9) SO₂(g), which may be produced from one or more calcining         steps, may be absorbed in a solution comprising water to form         aqueous sulfur dioxide. Said aqueous sulfur dioxide may be         transferred to step ‘(1)’. In some embodiments, make-up SO₂ may         be added to make-up for any SO₂ losses.         Description of Additional Metal Oxide Production Embodiments

Some embodiments of the present invention may involve reacting a material comprising calcium and magnesium with aqueous sulfur dioxide to form calcium sulfite and/or magnesium sulfite. Some embodiments of the present invention may involve reacting a material comprising calcium carbonate and magnesium carbonate with aqueous sulfur dioxide to form calcium sulfite and/or magnesium sulfite and/or captured carbon dioxide. Some embodiments may involve reacting the material comprising calcium and magnesium under conditions to form sulfites and avoid or minimize the formation of bisulfites. Some embodiments may involve exploiting the solubility difference between calcium sulfite and magnesium sulfite too enable the separation of at least a portion of magnesium sulfite from calcium sulfite. For example, magnesium sulfite may be soluble in water, while calcium sulfite may be practically insoluble in water.

Magnesium sulfite may be separated from at least a portion of calcium sulfite, or calcium carbonate, or magnesium carbonate, or other practically insoluble materials. Calcium sulfite is practically insoluble in water, with a solubility of 0.043 grams per liter at 18° C. Magnesium sulfite is soluble in water, with a solubility of 5.2 grams per liter at 25° C. The reaction of a material comprising calcium and magnesium with aqueous sulfur dioxide may result in the formation of at least a portion of a solid phase comprising calcium and at least a portion of an aqueous phase comprising magnesium sulfite.

Recovering magnesium sulfite from an aqueous solution comprising magnesium sulfite may be conducted using one or more or a combination of methods from separating a dissolved salt from an aqueous solution. Some properties of aqueous magnesium sulfite may enable simple, or low energy, or high throughput, or a combination thereof separation of solid magnesium sulfite from a solution comprising aqueous magnesium sulfite. For example, the solubility of magnesium sulfite increases with temperature—according to Solubilities of magnesium sulfite hydrates by Sohnel, et al, the solubility of magnesium sulfite or magnesium sulfite hexahydrate is 11.04 grams per liter at 43.0° C., or 14.19 grams per liter at 51.4° C., or 19.30 grams per liter at 61.4° C., or 28.87 grams per liter at 71.5° C., or 40.17 grams per liter at 79.0° C., or 53.73 grams per liter at 84.1° C., or 71.21 grams per liter at 88.0° C., or 95.19 grams per liter at 94.0° C. In some embodiments, the reaction of aqueous sulfur dioxide with a material comprising calcium and/or magnesium may be conducted at an elevated temperature, such as, for example, greater than room temperature, or greater than ambient air temperature, or greater than 25° C., or greater than 35° C., or greater than 45° C., or greater than 55° C., or greater than 65° C., or greater than 75° C., or greater than 85° C., or greater than 95° C., or greater than 100° C., or less than the boiling point of the solution at the pressure of the reactor, or greater than 105° C. By conducting at an elevated temperature, the concentration of magnesium sulfite in the aqueous magnesium sulfite may be greater, or the rate of reaction may be greater, or a combination thereof.

Regardless of the temperature of the reaction of aqueous sulfur dioxide with a material comprising calcium and/or magnesium, it may be desirable to concentrate the aqueous magnesium sulfite before or during the precipitation of aqueous magnesium sulfite. It may be desirable for at least a portion of said solution to be concentrated. It may be desirable for at least a portion of said solution to be concentrated using distillation. It may be desirable for at least a portion of said solution to be concentrated using a membrane based process at an elevated temperature. It may be desirable for at least a portion of said solution to be concentrated using a forward osmosis at an elevated temperature. It may be desirable for at least a portion of said solution to be heated before or during concentrating. It may be desirable for at least a portion of said solution to be heated before or during concentrating, to, for example, enable greater solubility of aqueous magnesium sulfite. It may be desirable for said aqueous magnesium sulfite to be treated to prevent scaling during concentrating, or to remove at least a portion of non-magnesium sulfite impurities, or a combination thereof. It may be desirable for at least a portion of said solution to be concentrated using a membrane-based process. For example, said aqueous magnesium sulfite solution may comprise a feed solution to a reverse osmosis process, wherein the reverse osmosis process separates said aqueous magnesium sulfite solution into a permeate comprising water and a concentrate comprising a greater concentration of aqueous magnesium sulfite. Said permeate comprising water may be transferred to a countercurrent heat exchanger for heat recovery and/or to a sulfur dioxide absorption process. It may be desirable for the reverse osmosis process to concentrate magnesium sulfite and/or other salts to a concentration less than their solubility limits to minimize membrane scaling. It may be desirable for the solution to be at an elevation temperature during the reverse osmosis process due to the greater solubility limit of magnesium sulfite with higher temperature and/or to prevent scaling or precipitation during reverse osmosis concentrating. Said concentrate comprising aqueous magnesium sulfite may be cooled to precipitate at least a portion of magnesium sulfite solid, due to, for example, the lesser solubility of magnesium sulfite in water with decreasing temperature, and/or said magnesium sulfite solid may be separated using a solid-liquid separation process. The remaining solution after separating magnesium sulfite solid using a solid-liquid separate process may comprise residual dissolved magnesium sulfite and/or dissolved non-magnesium sulfite salts or chemicals, and/or may undergo further treatment. For example, said remaining solution after separating magnesium sulfite solid using a solid-liquid separate process may be heated and/or transferred or mixed with said feed solution to the reverse osmosis process. For example, said remaining solution after separating magnesium sulfite solid using a solid-liquid separate process may undergo further reverse osmosis steps. For example, said remaining solution after separating magnesium sulfite solid using a solid-liquid separate process may be heated and/or transferred to another membrane-based process. For example, said remaining solution after separating magnesium sulfite solid using a solid-liquid separate process may be distilled and/or crystalized, which may further separate water from dissolved chemicals and/or separate magnesium sulfite from other salts or chemicals. For example, said remaining solution after separating magnesium sulfite solid using a solid-liquid separate process may be mixed with solution transferred to a sulfur dioxide absorption process. For example, said remaining solution after separating magnesium sulfite solid using a solid-liquid separate process may be further treated with, including, but not limited to, one or more or a combination of the following: ion exchange, or resins, or filters, or chemical treatments, or chemical reactions, or membrane based process, or distillation, or multi-effect distillation, or mechanical vapor recompression distillation, or mechanical vapor compression distillation, or multistage flash distillation, or membrane distillation, or cooling, or heating, or freezing, or crydesalination, or solventing-out, or solvent induced precipitation, or salting-out, or other treatment. One or more solutions comprising water may be transferred to a sulfur dioxide absorption step, or mixed with a solution transferred to a sulfur dioxide absorption step, or a combination thereof.

In some embodiments, the material comprising magnesium and calcium may further comprise impurities. In some embodiments, the material comprising magnesium carbonate and calcium carbonate may further comprise impurities. For example, the material comprising magnesium carbonate and calcium carbonate may further comprise magnesium sulfate, or calcium sulfate, or sodium salts, or potassium salts, or iron salts, or manganese salts, or silicon chemicals, or silicon salts, or aluminum salts, or zinc salts, or other salts. Additionally, the aqueous solution comprising magnesium sulfite may be exposed to diatomic oxygen or inadvertently exposed to diatomic oxygen, which may result in a portion of the magnesium sulfite converting to magnesium sulfate. In some embodiments, impurities in the solution comprising aqueous magnesium sulfite may comprise dissolved salts or other chemicals other than magnesium sulfite. In some embodiments, although certain chemicals may be classified as ‘impurities’, some ‘impurities’ may comprise valuable products. For example, impurities comprising calcium sulfate and/or magnesium sulfate may be separated and may comprise valuable products. In some embodiments, at least a portion of impurities may be separated from an aqueous solution comprising magnesium sulfite before, or during, or after magnesium sulfite concentrating and/or precipitation of magnesium sulfite. In some embodiments, potential impurities may be practically insoluble in the aqueous magnesium sulfite solution. For example, iron sulfite, or manganese sulfite may be practically insoluble in water if the formation of bisulfite salts is avoided or minimized by employing stoichiometric concentrations of aqueous sulfur dioxide, and/or minimizing residence time. Calcium sulfite solid may comprise other chemicals than calcium sulfite, which may include, but are not limited to, non-calcium sulfite salts described herein.

Calcium sulfite produced from a reaction with aqueous sulfur dioxide may comprise wet calcium sulfite. Wet calcium sulfite may be physically wetted, as in wet calcium sulfite may contain water on the surface of the solid or embedded within the solid. Wet calcium sulfite may comprise hydrated calcium sulfite, which contains a chemically reacted hydrate or wherein water is reacted or part of the calcium sulfite solid. Dry calcium sulfite may comprise calcium sulfite solid which has minimal or no water on its surface or is not physically wetted. Dry calcium sulfite may comprise calcium sulfite solid which is anhydrous. In some embodiments, dry calcium sulfite may comprise calcium sulfite solid may comprise calcium sulfite solid which is partially hydrated, which means it may comprise hydrates of calcium sulfite, although is less hydrated than the potential full hydrate capacity of the calcium sulfite. Transforming wet calcium sulfite to dry calcium sulfite may require energy. Transforming wet calcium sulfite to dry calcium sulfite may comprise ‘drying’. Some embodiments may involve employing wet calcium sulfite as an input to a calcining process to produce calcium oxide. Employing wet calcium sulfite as an input to a calcining process to produce calcium oxide may require more energy than employing dry calcium sulfite. Additionally, the amount and/or quality of energy required to calcine wet calcium sulfite may greater than if the wet calcium sulfite is dried into dry calcium sulfite before calcining. One or more or a combination of systems and methods may be employed to dry or dehydrate calcium sulfite. For example, calcium sulfite may be dried by heating the wet calcium sulfite to liberate water as a liquid or a vapor or both and separating said liberated water. If heating is employed, it may be desirable for the temperature of the heat employed to be less than the temperature of calcining calcium sulfite, or for the energy consumed to provide said heat to be less expensive or less carbon emission intensive than the energy consumed to calcine calcium sulfite, or a combination thereof. For example, said heat may be provided by, including, but not limited to, solar thermal, or heat pump, or waste heat, or steam, or low pressure steam, or stored heat, or process heat, or geothermal heat, or nuclear heat, or co-gen heat, or any combination thereof. For example, calcium sulfite may be dried by a carrier gas or stripping gas. For example, calcium sulfite may be dried by a recirculating carrier gas. For example, said recirculating carrier gas may comprise a gas or gas mixture with a diatomic oxygen concentration less than 2 percent by volume. For example, calcium sulfite may be dried by a recirculating carrier gas, wherein at least a portion of water vapor in the recirculating carrier gas is removed by a regenerable liquid desiccant. For example, calcium sulfite may be dried by a recirculating carrier gas, wherein at least a portion of water vapor in the recirculating carrier gas is removed by a regenerable liquid desiccant, which may include, but is not limited to, a glycol liquid desiccant, or glycol dehydration system, or a salt brine, or lithium bromide, or calcium chloride, or a liquid-liquid phase transition liquid desiccant, or a liquid desiccant regenerated by heat, or a liquid desiccant regenerated by vaporization of water, or a liquid desiccant regenerated by freezing desalination, or a liquid desiccant regenerated by a liquid-liquid phase transition into a water-rich phase and a water-lean phase, or a combination thereof. For example, calcium sulfite may be dried by a recirculating carrier gas, wherein at least a portion of water vapor in the recirculating carrier gas is removed by a regenerable solid desiccant, which may include, but is not limited to, an adsorbent, or gypsum, or silicate, or silica gel, or calcium oxide-calcium hydroxide, or a combination thereof. For example, calcium sulfite may be dried by a liquid desiccant, or a solid desiccant, or a combination thereof. For example, calcium sulfite may be dried by a recirculating carrier gas, wherein at least a portion of water vapor in the recirculating carrier gas is removed by a non-regenerated desiccant, which may comprise a solid or a liquid. For example, a non-regenerated desiccant may comprise a material which reacts with water to form a product, which may be removed from the process as a valuable product, or is disposed. For example, an example non-regenerated solid desiccant may comprise calcium oxide reacted with water or water vapor to form calcium hydroxide. For example, in some embodiments, calcium oxide produced by the process may be reacted with water vapor in said carrier gas, removing at least a portion of said water vapor while forming calcium hydroxide. Said calcium hydroxide may comprise a valuable product, or may be further reacted with water, or may be converted into other derivatives of calcium hydroxide. In some embodiments, at least a portion of heat generated from forming calcium hydroxide, from, for example, calcium oxide, may be employed to power at least a portion of the energy required to dry the wet calcium sulfite solid.

Magnesium sulfite solid produced in one or more steps of the process may comprise wet magnesium sulfite. Wet magnesium sulfite may be physically wetted, as in wet magnesium sulfite may contain water on the surface of the solid or embedded within the solid. Wet magnesium sulfite may comprise hydrated magnesium sulfite solid, which contains a chemically reacted hydrate or wherein water is reacted or part of the magnesium sulfite solid. Dry magnesium sulfite may comprise magnesium sulfite solid which has minimal or no water on its surface or is not physically wetted. Dry magnesium sulfite may comprise magnesium sulfite solid which is anhydrous. In some embodiments, dry magnesium sulfite may comprise magnesium sulfite solid and/or may comprise magnesium sulfite solid which is partially hydrated, which means it may comprise hydrates of magnesium sulfite, although is less hydrated than the potential full hydrate capacity of the magnesium sulfite. Transforming wet magnesium sulfite into dry magnesium sulfite may require energy. Transforming wet magnesium sulfite to dry magnesium sulfite may comprise ‘drying’. Some embodiments may involve employing wet magnesium sulfite as an input to a calcining process to produce magnesium oxide. Employing wet magnesium sulfite as an input to a calcining process to produce magnesium oxide may require more energy than employing dry magnesium sulfite. Additionally, the amount and/or quality of energy required to calcine wet magnesium sulfite may greater than if the wet magnesium sulfite is dried into dry magnesium sulfite before calcining. One or more or a combination of systems and methods may be employed to dry or dehydrate magnesium sulfite. For example, magnesium sulfite may be dried by heating the wet magnesium sulfite to liberate water as a liquid or a vapor or both and separating said liberated water. If heating is employed, it may be desirable for the temperature of the heat employed to be less than the temperature of calcining magnesium sulfite, or for the energy consumed to provide said heat to be less expensive or less carbon emission intensive than the energy consumed to calcine magnesium sulfite, or a combination thereof. For example, said heat may be provided by, including, but not limited to, solar thermal, or heat pump, or waste heat, or steam, or low pressure steam, or stored heat, or process heat, or geothermal heat, or nuclear heat, or co-gen heat, or any combination thereof. For example, magnesium sulfite may be dried by a carrier gas or stripping gas. For example, magnesium sulfite may be dried by a recirculating carrier gas. For example, said recirculating carrier gas may comprise a gas or gas mixture with a diatomic oxygen concentration less than 2 percent by volume. For example, magnesium sulfite may be dried by a recirculating carrier gas, wherein at least a portion of water vapor in the recirculating carrier gas is removed by a regenerable liquid desiccant. For example, magnesium sulfite may be dried by a recirculating carrier gas, wherein at least a portion of water vapor in the recirculating carrier gas is removed by a regenerable liquid desiccant, which may include, but is not limited to, a glycol liquid desiccant, or glycol dehydration system, or a salt brine, or lithium bromide, or calcium chloride, or a liquid-liquid phase transition liquid desiccant, or a liquid desiccant regenerated by heat, or a liquid desiccant regenerated by vaporization of water, or a liquid desiccant regenerated by freezing desalination, or a liquid desiccant regenerated by a liquid-liquid phase transition into a water-rich phase and a water-lean phase, or a combination thereof. For example, magnesium sulfite may be dried by a recirculating carrier gas, wherein at least a portion of water vapor in the recirculating carrier gas is removed by a regenerable solid desiccant, which may include, but is not limited to, an adsorbent, or gypsum, or silicate, or silica gel, or calcium oxide-calcium hydroxide, or an acid, or a combination thereof. For example, magnesium sulfite may be dried by a liquid desiccant, or a solid desiccant, or a combination thereof. For example, magnesium sulfite may be dried by a recirculating carrier gas, wherein at least a portion of water vapor in the recirculating carrier gas is removed by a non-regenerated solid desiccant. For example, a non-regenerated solid desiccant may comprise a material which reacts with water to form a product, which may be removed from the process as a valuable product, or may be disposed, or both. For example, an example non-regenerated solid desiccant may comprise calcium oxide reacted with water or water vapor to form calcium hydroxide. For example, in some embodiments, calcium oxide produced by the process may be reacted with water vapor in said carrier gas, removing at least a portion of said water vapor while forming calcium hydroxide. Said calcium hydroxide may comprise a valuable product, or may be further reacted with water, or may be converted into other derivatives of calcium hydroxide. In some embodiments, at least a portion of heat generated from forming calcium hydroxide, from, for example, calcium oxide, may be employed to power at least a portion of the energy required to dry the wet magnesium sulfite solid.

In some embodiments, said carrier gas may comprise high temperature steam. Said high temperature steam may be at a temperature greater than the temperature required to form gas phase water in the vapor-solid equilibrium of a hydrate of calcium sulfite, or a hydrate of magnesium sulfite, or any combination thereof.

In some embodiments, drying may be facilitated by mixing or directly contacting solid magnesium sulfite or solid calcium sulfite with a desiccant.

In some embodiments, calcium sulfite and/or magnesium sulfite may be contacted with or reacted with diatomic oxygen. For example, in some embodiments, calcium sulfite and/or magnesium sulfite may be reacted with diatomic oxygen to produce calcium sulfate and/or magnesium sulfate. For example, in in some embodiments, calcium sulfite and/or magnesium sulfite may be reacted with diatomic oxygen to produce calcium sulfate and/or magnesium sulfate and heat. For example, in in some embodiments, at portion of calcium sulfite and/or magnesium sulfite may be reacted with diatomic oxygen to produce heat and/or facilitate the dehydration or drying of calcium sulfite and/or magnesium sulfite. For example, diatomic oxygen may be present in the carrier gas to enable a reaction of a portion of the calcium sulfite, or magnesium sulfite, or both with diatomic oxygen, which may result the production of at least a portion of heat and/or the dehydration or drying of at least a portion of calcium sulfite or magnesium sulfite. In some embodiments, a portion of calcium sulfite may be reacted with diatomic oxygen to produce heat, and/or calcium sulfate, and/or dry stripping or carrier gas, and/or low oxygen dry stripping or carrier gas, and said low oxygen and/or drying stripping or carrier gas may be contacted with wet magnesium sulfite to form dry magnesium sulfite.

In some embodiments it may be desirable to react calcium sulfite with oxygen to from calcium sulfate or gypsum, which may comprise a valuable product from the process. In some embodiments it may be desirable to react magnesium sulfite with oxygen to from magnesium sulfate, which may comprise a valuable product from the process.

In some embodiments, at least a portion of the concentrate solution comprising magnesium sulfite, or solution comprising magnesium sulfite, or the solution comprising magnesium sulfite after the precipitation of at least a portion of magnesium sulfite may be distilled. For example, distilling said one or more solutions may enable the separation of various impurities due to, for example, the difference in solubility of various impurities and the tendency of some salts to precipitate at different points or different times or different concentrations due to differences in solubility or solubility properties. A solid-liquid separation process may be employed to separate at least a portion of a solid precipitate from a remaining liquid solution.

Example Figure Key

Example Figure Key for FIG. 11 Label Description  1 ‘1’ may comprise a material comprising calcium and/or magnesium. ‘1’ may comprise a solid material comprising calcium - weak acid, or magnesium - weak acid, or any combination thereof. ‘1’ may comprise calcium carbonate, or magnesium carbonate, or any combination thereof. ‘1’ may comprise a calcium silicate, or magnesium silicate, or any combination thereof. ‘1’ may comprise a carbonate, or a silicate, or a ferrite, or an aluminate, or manganese, or iron, or aluminum, or zinc, or any combination thereof.  2 ‘2’ may comprise a mixing vessel or reactor or a combination thereof. ‘2’ may comprise a process for reacting a material comprising magnesium and/or calcium with aqueous sulfur dioxide. ‘2’ may comprise a process for reacting a material comprising magnesium and/or calcium with aqueous sulfur dioxide to produce magnesium sulfite, and/or calcium sulfite. ‘2’ may comprise a process for reacting a material comprising magnesium and/or calcium with aqueous sulfur dioxide to produce magnesium sulfite, and/or calcium sulfite and/or carbon dioxide. ‘2’ may be designed to operate at least a portion of time at a pressure greater than atmospheric pressure, wherein carbon dioxide generated increases the total pressure to greater than 1 atm, or wherein carbon dioxide generated possesses a partial pressure greater than 1 atm, or a combination thereof. ‘2’ may operate in a batch, or semi-batch, or continuous, or a combination thereof fashion. ‘2’ may operate at an elevated temperature to facilitate reaction kinetics. For example, ‘2’ may operate at a temperature greater than 25° C. For example, ‘2’ may operate at a temperature greater than 25° C. and less than 100° C. For example, ‘2’ may operate at a temperature greater than 25° C. and less than the boiling point of the liquids present in ‘2’ at the total pressure of ‘2’. In some embodiments, ‘2’ may be heated. In some embodiments, one or more reactions present in ‘2’ may be exothermic and may result in an increase in temperature of one or more reagents or reactants or products in ‘2’. In some embodiments, ‘2’ may operate at a cold temperature, such as a temperature less than 25° C. In some embodiments, ‘2’ may be cooled. ‘2’ may operate under conditions or residence times or both to enable the formation of dissolved magnesium sulfite, while minimizing the formation of bisulfites. In some embodiments, ‘2’ may be cooled. ‘2’ may operate under conditions or residence times or both to enable the formation of dissolved magnesium sulfite, while minimizing the formation of calcium bisulfite, or iron bisulfite, or manganese bisulfite, or any combination thereof. In some embodiments, ‘2’ may be cooled. ‘2’ may operate under conditions or residence times or both to enable the formation of dissolved magnesium sulfite, while minimizing the formation of magnesium bisulfite, or calcium bisulfite, or iron bisulfite, or manganese bisulfite, or any combination thereof. For example, ‘2’ may involve a stoichiometric ratio of aqueous sulfur dioxide to magnesium and/or calcium to form magnesium sulfite and/or calcium sulfite, while minimizing the formation of calcium bisulfite, which may include, but is not limited to, a stoichiometric ratio less than 2 moles aqueous sulfur dioxide to 1 mole of magnesium and/or calcium, or a stoichiometric ratio less than 1.5 moles aqueous sulfur dioxide to 1 mole of magnesium and/or calcium, or a stoichiometric ratio less than 1.25 moles aqueous sulfur dioxide to 1 mole of magnesium and/or calcium, or a stoichiometric ratio less than 1.1 moles aqueous sulfur dioxide to 1 mole of magnesium and/or calcium, or any combination thereof. For example, ‘2’ may involve a residence time sufficient to form aqueous magnesium sulfite, although insufficient to substantially form aqueous calcium bisulfite. For example, ‘2’ may involve a residence time sufficient to form a concentration of at least 1 gram per liter of aqueous magnesium sulfite, although insufficient to form at least 1 gram per liter of aqueous calcium bisulfite. For example, ‘2’ may involve a residence time sufficient to form a concentration of at least 2 gram per liter of aqueous magnesium sulfite, although insufficient to form at least 1 gram per liter of aqueous calcium bisulfite.  3 ‘3’ may comprise a gas or gas mixture generated from the reaction of a material comprising magnesium and/or calcium with sulfurous acid. ‘3’ may comprise carbon dioxide. ‘3’ may comprise hydrogen sulfide. ‘3’ may comprise captured carbon dioxide, wherein at least a portion of said captured carbon dioxide is a purity of carbon dioxide is greater than 85% by volume, or greater than 90% by volume, or greater than 95% by volume, or any combination thereof. ‘3’ may comprise captured carbon dioxide, wherein at least a portion of said captured carbon dioxide is at a partial pressure greater than 0.5 atm pressure, or greater than 1 atm pressure, or greater than 1.5 atm pressure, or greater than 2 atm pressure, or greater than 2.5 atm pressure, or any combination thereof.  4 ‘4’ may comprise a solid-liquid mixture comprising calcium sulfite, or magnesium sulfite, or water, or any combination thereof. ‘4’ may comprise a solid-liquid mixture comprising a solid phase comprising calcium sulfite and a liquid phase comprising aqueous magnesium sulfite.  5 ‘5’ may comprise a solid-liquid separation process. ‘5’ may comprise a process for separating a solid-liquid mixture comprising a solid phase comprising calcium sulfite and a liquid phase comprising aqueous magnesium sulfite, into a substantially separate solid phase comprising calcium sulfite and a substantially separate liquid phase comprising aqueous magnesium sulfite.  6 ‘6’ may comprise a liquid comprising aqueous magnesium sulfite.  7 ‘7’ may comprise a process for separating at least a portion of water from at least a portion of aqueous magnesium sulfite or magnesium sulfite. ‘7’ may comprise a process for concentrating and/or precipitating magnesium sulfite. ‘7’ may comprise a process for removing at least a portion of non-magnesium sulfite impurities, if any. ‘7’ may comprise a process involving concentrating aqueous magnesium sulfite using elevated temperature reverse osmosis and precipitating at least a portion of magnesium sulfite solid from the formed concentrate by cooling said concentrate. The solubility of magnesium sulfite increases significantly with increasing temperature and decreases significantly with decreasing temperature. ‘7’ may involve a chemical reaction, or additives, or ion exchange, or electrodialysis, or other process to treat or remove non- magnesium sulfite impurities. ‘7’ may involve concentrating aqueous magnesium sulfite using electrodialysis. ‘7’ may involve distillation, or cryodesalination, or freezing desalination, or hydrate desalination, or a combination thereof. ‘7’ may involve a solid-liquid phase change, or a gas-liquid phase change, or a liquid-liquid phase transition, or any combination thereof. ‘7’ may involve a membrane based process, which may include, but is not limited to, reverse osmosis, or nanofiltration, or forward osmosis, or membrane distillation, or osmotically assistance reverse osmosis, or low salt rejection reverse osmosis, or DTRO, or any combination thereof. ‘7’ may involve multiple stages or steps.  8 ‘8’ may comprise water. ‘8’ may comprise water separated from an aqueous magnesium sulfite solution. At least a portion of ‘8’ may comprise a permeate separated from an aqueous magnesium sulfite feed solution using a membrane based process.  9 In some embodiments, a portion of magnesium sulfite may remain at an aqueous phase. ‘9’ may comprise remaining aqueous magnesium sulfite, which may comprise aqueous magnesium sulfite remaining after precipitating at least a portion of magnesium sulfite. ‘9’ may comprise remaining aqueous magnesium sulfite, which may comprise aqueous magnesium sulfite remaining after precipitating at least a portion of magnesium sulfite from a solution comprising magnesium sulfite concentrate. ‘9’ may comprise remaining aqueous magnesium sulfite which may be employed as a portion of liquid employed to absorb gaseous sulfur dioxide in, for example, later steps. 10 In some embodiments, a portion of magnesium sulfite may remain at an aqueous phase. ‘10’ may comprise remaining aqueous magnesium sulfite, which may comprise aqueous magnesium sulfite remaining after precipitating at least a portion of magnesium sulfite. ‘10’ may comprise remaining aqueous magnesium sulfite, which may comprise aqueous magnesium sulfite remaining after precipitating at least a portion of magnesium sulfite from a solution comprising magnesium sulfite concentrate. ‘10’ may comprise remaining aqueous magnesium sulfite which may be employed as a portion of the solution present before, or during, or after, or a combination thereof reacting aqueous sulfur dioxide with a material comprising magnesium and/or calcium. 11 In some embodiments, some non-magnesium or non-magnesium sulfite impurities may be present in a solution comprising aqueous magnesium sulfite. In some embodiments, at least a portion of said impurities may be separated. ‘11’ may comprise at least a portion of said impurities. In some embodiments, at least a portion of said separated impurities may comprise a valuable product. In some embodiments, at least a portion of said separated impurities may comprise a waste product. 12 ‘12’ may comprise solid magnesium sulfite. ‘12’ may comprise solid magnesium sulfite separated from an aqueous solution comprising aqueous magnesium sulfite. ‘12’ may comprise wet magnesium sulfite, or a hydrate of magnesium sulfite, or a combination thereof. 13 ‘13’ may comprise a process for drying, or dehydrating, or both solid magnesium sulfite. ‘13’ may involve heating. ‘13’ may involve drying or dehydrating with a liquid desiccant. ‘13’ may involve drying or dehydrating with a solid desiccant. ‘13’ may involve drying with a carrier gas. ‘13’ may involve drying with a carrier gas, wherein at least a portion of water is removed from said carrier gas by a regenerable liquid desiccant. ‘13’ may involve drying with a carrier gas, wherein at least a portion of water is removed from said carrier gas by a regenerable solid desiccant. ‘13’ may involve drying with a carrier gas, wherein at least a portion of water is removed from said carrier gas by a non-regenerable liquid desiccant. ‘13’ may involve drying with a carrier gas, wherein at least a portion of water is removed from said carrier gas by a non-regenerable solid desiccant. ‘13’ may involve drying with a carrier gas, wherein at least a portion of water is removed from said carrier gas by the reaction of calcium oxide with water to form calcium hydroxide. ‘13’ may involve drying with a carrier gas, wherein at least a portion of water is removed from said carrier gas by the reaction of at least partially dehydrated calcium sulfate with water to form hydrated calcium sulfate. ‘13’ may involve heating to a temperature less than 100° C. ‘13’ may involve heating to a temperature greater than 20° C. and less than 800° C. ‘13’ may involve multiple stages or steps. 14 ‘14’ may comprise dry, or partially dried, or dehydrated, or partially dehydrated, or a combination thereof magnesium sulfite solid. 15 ‘15’ may comprise a process for decomposing magnesium sulfite into at least a portion of a solid comprising magnesium oxide and a gas comprising sulfur dioxide. ‘15’ may comprise a calcining process. ‘15’ may comprise a shaft kiln, or a rotating kiln, or a batch kiln, or a continuous kiln, or a parallel flow regenerative shaft kiln, or a high performance shaft kiln, a annular shaft kiln, or a suspension calciner, or a preheater rotary kiln, or any combination thereof. ‘15’ may be conducted in a low oxygen environment. ‘15’ may be conducted in a low oxygen environment, wherein the concentration of gaseous diatomic oxygen is less than 1 volume percent, or 2 volume percent, or 3 volume percent, or a combination thereof. ‘15’ may be powered by the combustion of fuel, which may include, but is not limited to, one or more or a combination of the following: carbon fuel, or hydrocarbon, or hydrogen, or ammonia, or sulfur, or nitrogenous fuel, or any combination thereof. ‘15’ may be powered by solar thermal. ‘15’ may be powered electric heating or heating derived from electricity. ‘15’ may be powered by nuclear energy derived heat. 16 ‘16’ may comprise a gas comprising sulfur dioxide. At least a portion of ‘16’ may comprise a gas comprising sulfur dioxide produced from the decomposition of magnesium sulfite. ‘16’ may comprise a gas mixture comprising sulfur dioxide and one or more other gases. ‘16’ may comprise a gas mixture comprising sulfur dioxide, nitrogen, and a concentration of diatomic oxygen less than 5 volume percent. ‘16’ may comprise a gas mixture comprising sulfur dioxide, nitrogen, and a concentration of diatomic oxygen less than 2 volume percent. ‘16’ may comprise a gas mixture comprising sulfur dioxide, nitrogen, and water vapor. ‘16’ may comprise a gas mixture comprising sulfur dioxide and water vapor, wherein at least a portion of water vapor is condensed and/or at least a portion of heat is recovered from the exothermic condensing said water vapor. ‘16’ may comprise a gas mixture comprising at least a portion of sulfur dioxide and water vapor, wherein at least a portion of water vapor is condensed and/or at least a portion of heat is recovered from the exothermic condensing said water vapor and/or wherein at least a portion of sulfur dioxide dissolves in said condensed water to form aqueous sulfur dioxide. 17 ‘17’ may comprise magnesium oxide. ‘17’ may comprise magnesium oxide produce from the decomposition of magnesium oxide. ‘17’ may comprise residual magnesium sulfite. ‘17’ may comprise a portion of magnesium sulfate. ‘17’ may comprise residual magnesium sulfite. ‘17’ may comprise a portion of magnesium sulfate, which may comprise a residual contaminant. ‘17’ may comprise residual magnesium sulfite. ‘17’ may comprise a portion of magnesium sulfate, which may have formed due to a portion of magnesium sulfite reacting with a portion of diatomic oxygen. 18 ‘18’ may comprise the same as ‘17’. 19 ‘19’ may comprise solid calcium sulfite. ‘19’ may comprise solid calcium sulfite separated in a solid-liquid separation process from an aqueous solution comprising aqueous magnesium sulfite. ‘19’ may comprise wet calcium sulfite, or a hydrate of calcium sulfite, or a combination thereof. ‘19’ may comprise one or more chemicals in addition to calcium sulfite. For example, ‘19’ may comprise a portion of materials which did not dissolve in a reaction with aqueous sulfur dioxide. For example, ‘19’ may comprise a portion of silicon, or iron, or manganese, or zinc, or aluminum, or any combination thereof. 20 ‘20’ may comprise a process for drying, or dehydrating, or both solid calcium sulfite. ‘20’ may involve heating. ‘20’ may involve drying or dehydrating with a liquid desiccant. ‘20’ may involve drying or dehydrating with a solid desiccant. ‘20’ may involve drying with a carrier gas. ‘20’ may involve drying with a carrier gas, wherein at least a portion of water is removed from said carrier gas by a regenerable liquid desiccant. ‘20’ may involve drying with a carrier gas, wherein at least a portion of water is removed from said carrier gas by a regenerable solid desiccant. ‘20’ may involve drying with a carrier gas, wherein at least a portion of water is removed from said carrier gas by a non-regenerable liquid desiccant. ‘20’ may involve drying with a carrier gas, wherein at least a portion of water is removed from said carrier gas by a non-regenerable solid desiccant. ‘20’ may involve drying with a carrier gas, wherein at least a portion of water is removed from said carrier gas by the reaction of calcium oxide with water to form calcium hydroxide. ‘20’ may involve drying with a carrier gas, wherein at least a portion of water is removed from said carrier gas by the reaction of at least partially dehydrated calcium sulfate with water to form hydrated calcium sulfate. ‘20’ may involve heating to a temperature less than 100° C. ‘20’ may involve heating to a temperature greater than 20° C. and less than 800° C. ‘20’ may involve multiple stages or steps. 21 ‘21’ may comprise dry, or partially dried, or dehydrated, or partially dehydrated, or a combination thereof calcium sulfite solid. 22 ‘22’ may comprise a process for decomposing calcium sulfite into at least a portion of a solid comprising calcium oxide and a gas comprising sulfur dioxide. ‘22’' may comprise a calcining process. ‘22’ may comprise a shaft kiln, or a rotating kiln, or a batch kiln, or a continuous kiln, or a parallel flow regenerative shaft kiln, or a high performance shaft kiln, a annular shaft kiln, or a suspension calciner, or a preheater rotary kiln, or any combination thereof. ‘22’ may be conducted in a low oxygen environment. ‘22’ may be conducted in a low oxygen environment, wherein the concentration of gaseous diatomic oxygen is less than 1 volume percent, or 2 volume percent, or 3 volume percent, or a combination thereof. ‘22’ may be powered by the combustion of fuel, which may include, but is not limited to, one or more or a combination of the following: carbon fuel, or hydrocarbon, or hydrogen, or ammonia, or sulfur, or nitrogenous fuel, or any combination thereof. ‘22’ may be powered by solar thermal. ‘22’ may be powered by nuclear energy derived heat. ‘22’ may be powered electric heating or heating derived from electricity. 23 ‘23’ may comprise a gas comprising sulfur dioxide. At least a portion of ‘23’ may comprise a gas comprising sulfur dioxide produced from the decomposition of calcium sulfite. ‘23’ may comprise a gas mixture comprising sulfur dioxide and one or more other gases. ‘23’ may comprise a gas mixture comprising sulfur dioxide, nitrogen, and a concentration of diatomic oxygen less than 5 volume percent. ‘23’ may comprise a gas mixture comprising sulfur dioxide, nitrogen, and a concentration of diatomic oxygen less than 2 volume percent. ‘23’ may comprise a gas mixture comprising sulfur dioxide, nitrogen, and water vapor. ‘23’ may comprise a gas mixture comprising sulfur dioxide and water vapor, wherein at least a portion of water vapor is condensed and/ or at least a portion of heat is recovered from the exothermic condensing said water vapor. ‘23’ may comprise a gas mixture comprising at least a portion of sulfur dioxide and water vapor, wherein at least a portion of water vapor is condensed and/or at least a portion of heat is recovered from the exothermic condensing said water vapor and/ or wherein at least a portion of sulfur dioxide dissolves in said condensed water to form aqueous sulfur dioxide. 24 ‘24’ may comprise calcium oxide. ‘24’ may comprise calcium oxide produce from the decomposition of calcium oxide. ‘24’ may comprise residual calcium sulfite. ‘24’ may comprise a portion of calcium sulfate. ‘24’ may comprise residual calcium sulfite. ‘24’ may comprise a portion of calcium sulfate, which may comprise a residual contaminant. ‘24’ may comprise residual calcium sulfite. ‘24’ may comprise a portion of calcium sulfate, which may have formed due to a portion of calcium sulfite reacting with a portion of diatomic oxygen. 25 ‘25’ may comprise the same as ‘24’. 26 ‘26’ may comprise 'makeup' sulfur dioxide. In some embodiments, at least a portion of makeup sulfur dioxide is provided from the combustion of sulfur as at least a portion of a fuel in calcining or drying or both. In some embodiments, at least a portion of makeup sulfur dioxide is provided as an input to a process for absorbing sulfur dioxide. Makeup sulfur dioxide may be required to makeup for any sulfur dioxide losses. For example, sulfur dioxide losses may be due to residual reacted sulfur dioxide in the magnesium oxide, or calcium oxide, or non-magnesium sulfite impurities, or other output, or any combination thereof. For example, sulfur dioxide losses may be due to unabsorbed or unreacted sulfur dioxide. 27 ‘27’ may comprise a process for absorbing gaseous sulfur dioxide in a liquid solution. ‘27’ may comprise a process for absorbing gaseous sulfur dioxide in an aqueous solution. ‘27’ may comprise, including, but not limited to, an absorber, or a wash, or a contactor, or a column, or a membrane contactor, or a mixer, or any combination thereof. In some embodiments, ‘27’ may involve multiple stages, or multiple absorption solutions, or absorption solution inputs, or multiple absorption outputs, or one absorption output, or one absorption stage, or a merger of absorption solution inputs, or any combination thereof. 28 ‘28’ may comprise aqueous sulfur dioxide. ‘28’ may comprise a solution rich in aqueous sulfur dioxide. In some embodiments, ‘28’ may be pre-heated or heat exchanged before or while entering a process for reacting aqueous sulfur dioxide with a material comprising magnesium and/or calcium.

Example Exemplary Embodiments

1. A process for producing calcium oxide, magnesium oxide, or both from a material comprising calcium and magnesium wherein the process comprises:

reacting a material comprising calcium carbonate and magnesium carbonate with a solution comprising aqueous sulfur dioxide to form a gas comprising CO₂, a liquid solution comprising aqueous magnesium sulfite, and a solid comprising calcium sulfite;

separating said solid comprising calcium sulfite from said liquid solution comprising aqueous magnesium sulfite;

concentrating said aqueous magnesium sulfite using a membrane based process to form a concentrate solution comprising magnesium sulfite and a permeate comprising water;

precipitating solid magnesium sulfite from said concentrate solution comprising aqueous magnesium sulfite; and

calcining said solid calcium sulfite to produce calcium oxide or cement or calcining said solid magnesium sulfite to produce magnesium oxide or cement; wherein a drying step is conducted before said calcining, wherein at least a portion of heat for said drying is supplied by reacting calcium oxide with water, or reacting magnesium oxide with water, or both.

2. The process of embodiment 1 wherein said membrane based process comprises reverse osmosis, or forward osmosis, or both.

3. The process of embodiment 1 wherein said concentrating is conducted at a temperature greater than about 35° C. and less than about 100° C.

4. The process of embodiment 1 wherein said precipitating comprises cooling said concentrate solution to a temperature of less than about 35° C.

5. The process of embodiment 1 wherein said drying is at least partially conducted at a temperature less than a temperature of calcining.

6. The process of embodiment 1 wherein the concentration of CO₂ in the gas comprising CO₂ is greater than about 95 volume percent.

7. The process of embodiment 1 wherein the partial pressure of CO₂ in the gas comprising CO₂ is greater than about 1.5 atm.

8. The process of embodiment 1 wherein the calcining of calcium sulfite to calcium oxide, or the calcining of magnesium sulfite to magnesium oxide, or both further comprises forming a gas comprising sulfur dioxide.

9. The process of embodiment 8 further comprising absorbing at least a portion of said gas comprising sulfur dioxide into a solution comprising water to form aqueous sulfur dioxide.

10. The process of embodiment 9 wherein at least a portion of said solution comprising water comprises the permeate comprising water.

11. The process of embodiment 1 further comprising employing an anti-scaling chemical.

12. The process of embodiment 1 which further comprises heating a remaining solution after precipitating magnesium sulfite mixed said remaining solution with said aqueous magnesium sulfite before or during concentrating by the membrane based process.

13. The process of embodiment 1 which further comprises removing at least a portion of non-magnesium sulfite impurities from a remaining solution after precipitating magnesium sulfite.

14. The process of embodiment 1 which further comprising employing a remaining solution after precipitating magnesium sulfite to absorb at least a portion of any sulfur dioxide produced by calcining of calcium sulfite or calcining of magnesium sulfite.

15. The process of embodiment 1 which further comprises recovering at least a portion of any sulfur dioxide produced by calcining of calcium sulfite or calcining of magnesium sulfite by cryogenic separation.

16. The process of embodiment 1 wherein a carrier gas comprising water vapor is employed during drying and wherein the process further comprising removing at least a portion of water vapor from said carrier gas.

17. The process of embodiment 16 wherein the removing comprises reacting the water vapor with calcium oxide to form calcium hydroxide.

18. The process of embodiment 16 wherein the removing comprises reacting the water vapor with a non-regenerated desiccant.

19. The process of embodiment 16 wherein the removing comprises employing a liquid desiccant, or a solid desiccant, or both.

20. The process of embodiment 16 wherein the removing comprises employing a membrane-based process.

21. The process of embodiment 16 wherein the removing comprises condensing.

22. The process of embodiment 16 wherein said carrier gas comprises less than about 2 percent by volume of diatomic oxygen.

23. A process for producing magnesium oxide from a material comprising calcium and magnesium comprising:

reacting a material comprising calcium and magnesium with a solution comprising aqueous sulfur dioxide to form a liquid solution comprising aqueous magnesium sulfite, and a solid comprising calcium sulfite;

separating said solid comprising calcium sulfite from said liquid solution comprising aqueous magnesium sulfite;

concentrating said aqueous magnesium sulfite using a membrane-based process to form a concentrate solution comprising magnesium sulfite;

precipitating solid magnesium sulfite from said concentrate solution comprising aqueous magnesium sulfite; and

calcining said solid magnesium sulfite to produce magnesium oxide; wherein a drying step is conducted before said calcining, wherein at least a portion of heat for said drying is supplied by reacting calcium oxide with water, or reacting magnesium oxide with water, or both.

-   -   1. A process for producing calcium oxide and magnesium oxide and         captured carbon dioxide from a material comprising calcium and         magnesium comprising: Reacting a material comprising calcium and         magnesium carbonate with a solution comprising aqueous sulfur         dioxide to form a gas comprising captured CO₂, a liquid solution         comprising aqueous magnesium sulfite, and a solid comprising         calcium sulfite Separating said solid comprising calcium sulfite         from said liquid solution comprising aqueous magnesium sulfite         -   Concentrating said aqueous magnesium sulfite using a             membrane based process to form a concentrate solution             comprising magnesium sulfite and a permeate comprising water         -   Precipitating solid magnesium sulfite from said concentrate             solution comprising aqueous magnesium sulfite calcining said             solid calcium sulfite to produce calcium oxide or cement;             and calcining said solid magnesium sulfite to produce             magnesium oxide or cement.     -   2. The process of example exemplary embodiment 1 wherein said         membrane based process comprises reverse osmosis, or forward         osmosis, or both.     -   3. The process of example exemplary embodiment wherein said         concentrating is conducted at a temperature greater than 35° C.         and less than 100° C.     -   4. The process of example exemplary embodiment wherein said         precipitating is conducted by cooling said concentrate solution         to a temperature less than 35° C.     -   5. The process of example exemplary embodiment 1 wherein said         solid calcium sulfite, or solid magnesium sulfite, or both are         dried, or dehydrated, or both before calcining.     -   6. The process of example exemplary embodiment 5 wherein said         drying or dehydrating is at least partially conducted at a         temperature less than a temperature of calcining.     -   7. The process of example exemplary embodiment 5 wherein at         least a portion of heat for said drying or dehydrating is         supplied by reacting calcium oxide with water, or reacting         magnesium oxide with water, or both.     -   8. The process of example exemplary embodiment 5 wherein a         carrier gas comprising water vapor is employed during drying or         dehydrating and wherein at least a portion of water vapor is         removed from said carrier gas     -   9. The process of example exemplary embodiment 8 wherein at         least a portion of water vapor is removed from said carrier gas         by reacting the water vapor with calcium oxide to form calcium         hydroxide.     -   10. The process of example exemplary embodiment 8 wherein at         least a portion of water vapor is removed from said carrier gas         by reacting the water vapor with a non-regenerated desiccant.     -   11. The process of example exemplary embodiment 8 wherein at         least a portion of water vapor is removed from said carrier gas         by a liquid desiccant, or a solid desiccant, or both.     -   12. The process of example exemplary embodiment 8 wherein at         least a portion of water vapor is removed from said carrier gas         by a membrane-based process.     -   13. The process of example exemplary embodiment 8 wherein at         least a portion of water vapor is removed from said carrier gas         by condensing.     -   14. The process of example exemplary embodiment 8 wherein said         carrier gas comprises less than 2 percent by volume diatomic         oxygen.     -   15. The process of example exemplary embodiment 1 wherein the         concentration of CO₂ in the gas comprising captured CO₂ is         greater than 95 volume percent.     -   16. The process of example exemplary embodiment 1 wherein the         partial pressure of CO₂ in the gas comprising captured CO₂ is         greater than 1.5 atm.     -   17. The process of example exemplary embodiment 1 wherein the         calcining of calcium sulfite to calcium oxide, or the calcium of         magnesium sulfite to magnesium oxide, or both further comprises         forming a gas comprising sulfur dioxide.     -   18. The process of example exemplary embodiment 16 wherein at         least a portion of said gas comprising sulfur dioxide in         absorbed into a solution comprising water to form aqueous sulfur         dioxide.     -   19. The process of example exemplary embodiment 17 wherein at         least a portion of said solution comprising water comprises the         permeate produced by said membrane based process.     -   20. The process of example exemplary embodiment 1 wherein said         aqueous magnesium sulfite, or said concentrate, or both is/are         treated with a chemical to minimize membrane scaling in the         membrane based process.     -   21. The process of example exemplary embodiment 1 wherein the         remaining solution after precipitating magnesium sulfite is         heated and mixed with said aqueous magnesium sulfite before or         during concentrating by the membrane based process.     -   22. The process of example exemplary embodiment 1 wherein at         least a portion of the remaining solution after precipitating         magnesium sulfite is treated to remove at least a portion of         non-magnesium sulfite impurities.     -   23. The process of example exemplary embodiment 22 wherein said         treated solution is heated and mixed with the aqueous magnesium         sulfite before or during concentrating by the membrane based         process.     -   24. The process of example exemplary embodiment 1 wherein the         remaining solution after precipitating magnesium sulfite is         employed to absorb sulfur dioxide produced by the calcining of         calcium sulfite and magnesium sulfite.     -   25. The process of example exemplary embodiment 1 wherein at         least a portion of sulfur dioxide is recovered by cryogenic         separation.     -   26. The process of example exemplary embodiment 1 wherein at         least a portion of the remaining solution after precipitating         magnesium sulfite is distilled.     -   27. A process for producing calcium oxide and magnesium oxide         from a material comprising calcium and magnesium comprising:         -   Reacting a material comprising calcium and magnesium with             sulfur dioxide to form a solid comprising calcium sulfite             and magnesium sulfite         -   Contacting said solid comprising calcium sulfite and             magnesium sulfite with water to form a liquid solution             comprising aqueous magnesium sulfite         -   Separating said solid comprising calcium sulfite from said             liquid solution comprising aqueous magnesium sulfite     -   28. The process of example exemplary embodiment 26 further         comprising concentrating said aqueous magnesium sulfite using a         membrane based process to form a concentrate solution comprising         magnesium sulfite and a permeate comprising water     -   29. The process of example exemplary embodiment 26 further         comprising precipitating solid magnesium sulfite from said         concentrate solution comprising aqueous magnesium sulfite     -   30. The process of example exemplary embodiment 26 further         comprising drying said precipitated solid magnesium sulfite         using a carrier gas with a diatomic oxygen concentration less         than 3 volume percent.     -   31. A process for producing magnesium oxide from a material         comprising calcium and magnesium comprising:         -   Reacting a material comprising calcium and magnesium with a             solution comprising aqueous sulfur dioxide to form a liquid             solution comprising aqueous magnesium sulfite, and a solid             comprising calcium sulfite         -   Separating said solid comprising calcium sulfite from said             liquid solution comprising aqueous magnesium sulfite         -   Concentrating said aqueous magnesium sulfite using a             membrane-based process to form a concentrate solution             comprising magnesium sulfite         -   Precipitating solid magnesium sulfite from said concentrate             solution comprising aqueous magnesium sulfite         -   Calcining said solid magnesium sulfite to produce magnesium             oxide.             Carboxylic Acid Embodiments with Sulfite or Bisulfite             Overview

The present embodiments may pertain to a process for regenerating calcium in the production of or isolation of carboxylic acids, such as citric acid. Some embodiments may comprise a citric acid production process which regenerates calcium oxide or calcium carbonate. Some embodiments may eliminate or greatly reduce the need for virgin calcium oxide or calcium carbonate input and/or virgin sulfuric acid input. Some embodiments may eliminate or greatly reduce the production of calcium waste products or byproducts. Some embodiments may further comprise a process for capturing carbon dioxide and/or producing pure carbon dioxide gas.

Example Summary of Inputs and Outputs of an Example Embodiment Inputs Outputs Calcium Citrate CaO and/or Cement or or A Solution Comprising Citric Captured Carbon Dioxide Acid Requiring Recovery/ Separation of Citric Acid Or Carbon Dioxide or Carbonate Salt (Note: In some embodiments, the Calcium or magnesium may be recycled within a process and may comprise an intermediate rather than an input) Fuel Silicon dioxide or other Option A: Combustible fuel, such as a solid silicon derivative Carbonaceous Fuel and/or Sulfurous or aggregate or a Fuel and/or Hydrogen Fuel and/or combination thereof Nitrogenous Fuel Option B: Electricity, light, or Unreacted materials concentrated solar thermal, or a derivative thereof or similar energy or heat source Sulfurous Salt Waste-Product or Useful Byproduct Calcium Citrate to Calcium Oxide or Cement and Citric Acid (1) Ca₃(C₆H₅O₇)₂.H₂O(s)+3H₂SO₃(aq)→3CaSO₃(s)+2C₆H₈O₇(aq)+4H₂O(l or aq) (2) 2C₆H₈O₇(aq)→2C₆H₈O₇(s or conc. aq) (3) 3CaSO₃(s)+Heat→3CaO(s)+3SO₂(g) (4) 3SO₂(g)+3H₂O(l)→3H₂SO₃(aq) or (1) 2C₆H₈O₇(aq)+3Ca(OH)₂(aq)→Ca₃(C₆H₅O₇)₂→H₂O(s)+2H₂O(l) (2) Ca₃(C₆H₅O₇)₂.4H₂O(s)+3H₂SO₃(aq)→3CaSO₃(s)+2C₆H₈O₇(aq)+4H₂O(l or aq) (3) 2C₆H₈O₇(aq)→2C₆H₈O₇(s or conc. aq) (4) 3CaSO₃(s)+Heat→3CaO(s)+3SO₂(g) (5) 3SO₂(g)+3H₂O(l)→3H₂SO₃(aq) (6) 3CaO(s)+3H₂O→3Ca(OH)₂ (aq or s)+Heat or (1) 2C₆H₈O₇(aq)+3CaCO₃(aq)→Ca₃(C₆H₅O₇)₂.4H₂O(s)+3CO₂(g) (2) Ca₃(C₆H₅O₇)₂.4H₂O(s)+3H₂SO₃(aq)→3CaSO₃(s)+2C₆H₈O₇(aq)+4H₂O(l or aq) (3) 2C₆H₈O₇(aq)→2C₆H₈O₇(s or conc. aq) (4) 3CaSO₃(s)+Heat→3CaO(s)+3SO₂(g) (5) 3SO₂(g)+3H₂O(l)→3H₂SO₃(aq) (6) 3CaO(s)+3H₂O→3Ca(OH)₂ (aq or s)+Heat (7) 3Ca(OH)₂ (aq or s)+3CO₂(g or aq)→3CaCO₃(s)+3H₂O or (1) 2C₆H₈O₇(aq)+3CaCO₃(aq)→Ca₃(C₆H₅O₇)₂.4H₂O(s)+3CO₂(g) (2) Ca₃(C₆H₅O₇)₂.4H₂O(s)+3H₂SO₃(aq)→3CaSO₃(s)+2C₆H₈O₇(aq)+4H₂O(l or aq) (3) 2C₆H₈O₇(aq)→2C₆H₈O₇(s or conc. aq) (4) 3CaSO₃(s)+Heat→3CaO(s)+3SO₂(g) (5) 3SO₂(g)+3H₂O(l)→3H₂SO₃(aq) (6) 3CaO(s)+3H₂O→3Ca(OH)₂ (aq or s)+Heat (7) 3Ca(OH)₂ (aq or s)+3K₂CO₃(aq)→3CaCO₃(s)+6 KOH(aq) (8) 6 KOH(aq)+3CO₂→3K₂CO₃(aq)+3H₂O

Note: Calcium oxide may be recycled in a process for producing citric acid. Calcium may comprise an intermediate.

Note: 2C₆H₈O₇(aq) input may comprise a solution comprising a dilute concentration of citric acid or a solution comprising a mixture of citric acid with other solutes, such as sugars. Citric acid may be isolated or removed from said solution by reacting said solution with calcium hydroxide, producing calcium citrate solid precipitate, which is separated from the solution using a solid-liquid separation method, such as filtration, or centrifuge, or a combination thereof, or other method described herein, or other method described in the art.

Example Step-by-Step Description 1:

Step 1: Calcium hydroxide, which may comprise a solid, or liquid, or solid-liquid mixture, or solid-liquid suspension, or any combination thereof and/or may be from Step 6, may be reacted or mixed with a solution comprising aqueous citric acid, which may result in the formation of at least a portion of calcium citrate, which may comprise a solid. The aqueous citric acid may comprise water, or citric acid, or fermentation broth, or juice, or fruit, or sugar, or molasses, or microbial broth, or broth, or any combination thereof. Calcium citrate solid may be separated from the remaining solution by, for example, solid-liquid separation. Step 2: Calcium citrate, which may comprise a solid, may be reacted with aqueous sulfur dioxide or sulfurous acid, which may result in the formation of calcium sulfite, which may comprise a solid, and/or aqueous citric acid. In some embodiments, a portion of dissolved calcium bisulfite may form. The present step may be conducted in a mixing vessel or mixing reactor. In some embodiments, it may be desirable for the residence time to be sufficient for the reaction to occur. In some embodiments, is may be desirable for the residence time to be brief to prevent or minimize the formation of calcium bisulfite. In some embodiments, it may be desirable for the residence time to be sufficient to enable or facilitate the formation of dissolved calcium bisulfite. In some embodiments, the reaction of sulfur dioxide or sulfurous acid and calcium citrate may be continuous, or semi-continuous, or batch, or any combination thereof. Said solid calcium sulfite may be separated from said aqueous citric acid solution by, for example, a solid-liquid separation process, which may include, but is not limited to, a filter, or centrifuge, or decanter, or coalescer, or any combination thereof. Step 3: Aqueous citric acid, which may be from Step 2, may be concentrated and/or purified before transport, or sale, or use. For example, aqueous citric acid may be concentrated. For example, aqueous citric acid may be crystalized or isolated as a solid. In some embodiments, residual sulfur dioxide may be separated or desorbed from the aqueous citric acid solution. In some embodiments, water may be recovered or removed from the aqueous citric acid solution. For example, water may be recovered or removed by, including, but not limited to, one or more or any combination of the following: forward osmosis, or reverse osmosis, or a membrane based process, or distillation, or evaporation, or vacuum distillation, or salting out, or solventing out, or extraction, or crystallization of citric acid, or extraction of citric acid. In some embodiments, water and/or sulfur dioxide may be separated, or recovered from the aqueous citric acid solution and/or recycled or recirculated within the process. The separation of water and/or residual sulfur dioxide may require heat input, or depressurization, or vacuum, or vapor compression, or stripping gas, or a combination thereof. The present step may involve water removal, such as mechanical vapor compression distillation, or mechanical vapor re-compression distillation, or evaporation, or distillation, or membrane based process, or crystallization, or other separation processes described herein, or processes for separating citric acid from water in the art, or processes for purifying citric acid or citric acid solutions in the art, or water removal or separation processes described herein, or other water removal or separation processes described in the art, or other separation processes described in the art, or a combination thereof. The present step may produce, for example, solid citric acid, or a citric acid concentrate solution, or a combination thereof. Citric acid may be a product or output from the present step. Separated or recovered water may be transferred to step ‘6’. Step 4: Solid calcium sulfite may be calcined, which may result in the formation of calcium oxide and sulfur dioxide. In some embodiments, it may be desirable to at least partially dry or pre-heat the calcium sulfite before calcining the calcium sulfite. Step 5: Sulfur dioxide produced from, for example, Step 3, or Step 4, or makeup SO₂, or any combination thereof may be absorbed into water, or a solvent, or an aqueous solution, which may result in the formation of aqueous sulfur dioxide or sulfurous acid. The aqueous sulfurous acid may be transferred to Step 2. Step 6: Calcium oxide from, for example, Step 4, may be reacted or otherwise mixed with water, which may result in the formation of calcium hydroxide and heat. Calcium hydroxide may comprise, including, but not limited to, one or more or any combination of the following: a solid, or aqueous solution, or a solid-liquid mixture, or a solid-liquid suspension, or a non-Newtonian fluid, or milk of lime. Example Step-by-Step Description 2: Step 1: Calcium carbonate, which may comprise a solid, or liquid, or solid-liquid mixture, or solid-liquid suspension, or any combination thereof and/or may be from Step 7, may be reacted or mixed with a solution comprising aqueous citric acid, which may result in the formation of at least a portion of calcium citrate, which may comprise a solid, and may result in the formation of captured carbon dioxide. Said captured carbon dioxide may comprise a gas, or dissolved carbon dioxide, or any combination thereof. Said captured carbon dioxide may comprise gaseous carbon dioxide with a partial pressure greater than 0.25 Bar, or 0.50 Bar, or 0.75 Bar, or 1.00 Bar, or any combination thereof. Said captured carbon dioxide may be compressed, or treated, or transported, or used, or any combination thereof for one, or more, or any combination of utilization, or conversion, or storage applications. The aqueous citric acid may comprise water, or citric acid, or fermentation broth, or juice, or fruit, or sugar, or molasses, or microbial broth, or broth, or any combination thereof. Calcium citrate solid may be separated from the remaining solution by, for example, solid-liquid separation. In some embodiments, residual calcium citrate, which may comprise aqueous calcium citrate, may be recirculated, or remain in the broth, or may be at least partially separated, or any combination thereof. Step 2: Calcium citrate, which may comprise a solid, may be reacted with aqueous sulfur dioxide or sulfurous acid, which may result in the formation of calcium sulfite, which may comprise a solid, and/or aqueous citric acid. In some embodiments, a portion of dissolved calcium bisulfite may form. The present step may be conducted in a mixing vessel or mixing reactor. In some embodiments, it may be desirable for the residence time to be sufficient for the reaction to occur. In some embodiments, is may be desirable for the residence time to be brief to prevent or minimize the formation of calcium bisulfite. In some embodiments, it may be desirable for the residence time to be sufficient to enable or facilitate the formation of dissolved calcium bisulfite. In some embodiments, the reaction of sulfur dioxide or sulfurous acid and calcium citrate may be continuous, or semi-continuous, or batch, or any combination thereof. Said solid calcium sulfite may be separated from said aqueous citric acid solution by, for example, a solid-liquid separation process, which may include, but is not limited to, a filter, or centrifuge, or decanter, or coalescer, or any combination thereof. Step 3: Aqueous citric acid, which may be from Step 2, may be concentrated and/or purified before transport, or sale, or use. For example, aqueous citric acid may be concentrated. For example, aqueous citric acid may be crystalized or isolated as a solid. In some embodiments, residual sulfur dioxide may be separated or desorbed from the aqueous citric acid solution. In some embodiments, water may be recovered or removed from the aqueous citric acid solution. For example, water may be recovered or removed by, including, but not limited to, one or more or any combination of the following: forward osmosis, or reverse osmosis, or a membrane based process, or distillation, or evaporation, or vacuum distillation, or salting out, or solventing out, or extraction, or crystallization of citric acid, or extraction of citric acid. In some embodiments, water and/or sulfur dioxide may be separated, or recovered from the aqueous citric acid solution and/or recycled or recirculated within the process. The separation of water and/or residual sulfur dioxide may require heat input, or depressurization, or vacuum, or vapor compression, or stripping gas, or a combination thereof. The present step may involve water removal, such as mechanical vapor compression distillation, or mechanical vapor re-compression distillation, or evaporation, or distillation, or membrane based process, or crystallization, or other separation processes described herein, or processes for separating citric acid from water in the art, or processes for purifying citric acid or citric acid solutions in the art, or water removal or separation processes described herein, or other water removal or separation processes described in the art, or other separation processes described in the art, or a combination thereof. The present step may produce, for example, solid citric acid, or a citric acid concentrate solution, or a combination thereof. Citric acid may be a product or output from the present step. Separated or recovered water may be transferred to step ‘5’. Step 4: Solid calcium sulfite may be calcined, which may result in the formation of calcium oxide and sulfur dioxide. In some embodiments, it may be desirable to at least partially dry or pre-heat the calcium sulfite before calcining the calcium sulfite. Step 5: Sulfur dioxide produced from, for example, Step 3, or Step 4, or makeup SO₂, or any combination thereof may be absorbed into water, or a solvent, or an aqueous solution, which may result in the formation of aqueous sulfur dioxide or sulfurous acid. The aqueous sulfurous acid may be transferred to Step 2. Step 6: Calcium oxide from, for example, Step 4, may be reacted or otherwise mixed with water, which may result in the formation of calcium hydroxide and heat. Calcium hydroxide may comprise, including, but not limited to, one or more or any combination of the following: a solid, or aqueous solution, or a solid-liquid mixture, or a solid-liquid suspension, or a non-Newtonian fluid, or milk of lime. Step 7: Calcium hydroxide, which may be from Step 6, may be reacted with carbon dioxide, which may result in the formation of calcium carbonate and/or water. Alternatively or additionally, calcium oxide may be reacted with carbon dioxide, which may result in the formation of calcium carbonate. Carbon dioxide may comprise a gas stream or liquid, or solid, or any combination thereof comprising carbon dioxide, which may include, but is not limited to, one or more or any combination of the following: gaseous carbon dioxide, or air, or flue gas, or emissions gas, or fermentation gas, or natural gas, or biogas, or landfill gas, or natural CO₂, or carbonate salt, or bicarbonate salt, or aqueous carbon dioxide, or dissolved carbon dioxide, or non-aqueous carbon dioxide, or liquid carbon dioxide, or supercritical carbon dioxide, or solid carbon dioxide. The reaction of calcium hydroxide with carbon dioxide may comprise a carbon capture step, which may involve absorbing or separating carbon dioxide from a dilute source of carbon dioxide, such as air, or a source of carbon dioxide which may otherwise be emitted or wasted. Example Step-by-Step Description 3: Step 1: Calcium carbonate, which may comprise a solid, or liquid, or solid-liquid mixture, or solid-liquid suspension, or any combination thereof and/or may be from Step 7, may be reacted or mixed with a solution comprising aqueous citric acid, which may result in the formation of at least a portion of calcium citrate, which may comprise a solid, and may result in the formation of captured carbon dioxide. Said captured carbon dioxide may comprise a gas, or dissolved carbon dioxide, or any combination thereof. Said captured carbon dioxide may comprise gaseous carbon dioxide with a partial pressure greater than 0.25 Bar, or 0.50 Bar, or 0.75 Bar, or 1.00 Bar, or any combination thereof. Said captured carbon dioxide may be compressed, or treated, or transported, or used, or any combination thereof for one, or more, or any combination of utilization, or conversion, or storage applications. The aqueous citric acid may comprise water, or citric acid, or fermentation broth, or juice, or fruit, or sugar, or molasses, or microbial broth, or broth, or any combination thereof. Calcium citrate solid may be separated from the remaining solution by, for example, solid-liquid separation. In some embodiments, residual calcium citrate, which may comprise aqueous calcium citrate, may be recirculated, or remain in the broth, or may be at least partially separated, or any combination thereof. Step 2: Calcium citrate, which may comprise a solid, may be reacted with aqueous sulfur dioxide or sulfurous acid, which may result in the formation of calcium sulfite, which may comprise a solid, and/or aqueous citric acid. In some embodiments, a portion of dissolved calcium bisulfite may form. The present step may be conducted in a mixing vessel or mixing reactor. In some embodiments, it may be desirable for the residence time to be sufficient for the reaction to occur. In some embodiments, is may be desirable for the residence time to be brief to prevent or minimize the formation of calcium bisulfite. In some embodiments, it may be desirable for the residence time to be sufficient to enable or facilitate the formation of dissolved calcium bisulfite. In some embodiments, the reaction of sulfur dioxide or sulfurous acid and calcium citrate may be continuous, or semi-continuous, or batch, or any combination thereof. Said solid calcium sulfite may be separated from said aqueous citric acid solution by, for example, a solid-liquid separation process, which may include, but is not limited to, a filter, or centrifuge, or decanter, or coalescer, or any combination thereof. Step 3: Aqueous citric acid, which may be from Step 2, may be concentrated and/or purified before transport, or sale, or use. For example, aqueous citric acid may be concentrated. For example, aqueous citric acid may be crystalized or isolated as a solid. In some embodiments, residual sulfur dioxide may be separated or desorbed from the aqueous citric acid solution. In some embodiments, water may be recovered or removed from the aqueous citric acid solution. For example, water may be recovered or removed by, including, but not limited to, one or more or any combination of the following: forward osmosis, or reverse osmosis, or a membrane based process, or distillation, or evaporation, or vacuum distillation, or salting out, or solventing out, or extraction, or crystallization of citric acid, or extraction of citric acid. In some embodiments, water and/or sulfur dioxide may be separated, or recovered from the aqueous citric acid solution and/or recycled or recirculated within the process. The separation of water and/or residual sulfur dioxide may require heat input, or depressurization, or vacuum, or vapor compression, or stripping gas, or a combination thereof. The present step may involve water removal, such as mechanical vapor compression distillation, or mechanical vapor re-compression distillation, or evaporation, or distillation, or membrane based process, or crystallization, or other separation processes described herein, or processes for separating citric acid from water in the art, or processes for purifying citric acid or citric acid solutions in the art, or water removal or separation processes described herein, or other water removal or separation processes described in the art, or other separation processes described in the art, or a combination thereof. The present step may produce, for example, solid citric acid, or a citric acid concentrate solution, or a combination thereof. Citric acid may be a product or output from the present step. Separated or recovered water may be transferred to step ‘6’. Step 4: Solid calcium sulfite may be calcined, which may result in the formation of calcium oxide and sulfur dioxide. In some embodiments, it may be desirable to at least partially dry or pre-heat the calcium sulfite before calcining the calcium sulfite. Step 5: Sulfur dioxide produced from, for example, Step 3, or Step 4, or makeup SO₂, or any combination thereof may be absorbed into water, or a solvent, or an aqueous solution, which may result in the formation of aqueous sulfur dioxide or sulfurous acid. The aqueous sulfurous acid may be transferred to Step 2. Step 6: Calcium oxide from, for example, Step 4, may be reacted or otherwise mixed with water, which may result in the formation of calcium hydroxide and heat. Calcium hydroxide may comprise, including, but not limited to, one or more or any combination of the following: a solid, or aqueous solution, or a solid-liquid mixture, or a solid-liquid suspension, or a non-Newtonian fluid, or milk of lime. Heat generated from the reaction may be employed within the process or system, or in another application, or any combination thereof Step 7: Calcium hydroxide, which may be from Step 6, may be reacted with a carbonate, or bicarbonate, or carbamate, or any combination thereof salt, which may comprise an aqueous solution, or liquid, or solid, or any combination thereof, which may result in the formation of calcium carbonate and/or a hydroxide solution. For example, calcium hydroxide may be reacted with potassium carbonate or sodium carbonate, which may result in the formation of calcium carbonate and potassium hydroxide and/or sodium hydroxide. In some embodiments, the potassium hydroxide and/or sodium hydroxide may comprise a liquid or aqueous solution, which the calcium carbonate may comprise a solid. In some embodiments, the solid calcium carbonate may be separated from the aqueous potassium hydroxide and/or sodium hydroxide by, for example, a solid-liquid separation. Step 8: The aqueous hydroxide salt or aqueous hydroxide salt solution from, for example, Step 7, may be reacted with carbon dioxide from one or more or any combination of carbon dioxide sources. For example, potassium hydroxide or sodium hydroxide may be reacted or contacted with a gas comprising carbon dioxide, which may result in the formation of potassium carbonate or bicarbonate and/or sodium carbonate or bicarbonate. Carbon dioxide may comprise a gas stream or liquid, or solid, or any combination thereof comprising carbon dioxide, which may include, but is not limited to, one or more or any combination of the following: gaseous carbon dioxide, or air, or flue gas, or emissions gas, or fermentation gas, or natural gas, or biogas, or landfill gas, or natural CO₂, or carbonate salt, or bicarbonate salt, or aqueous carbon dioxide, or dissolved carbon dioxide, or non-aqueous carbon dioxide, or liquid carbon dioxide, or supercritical carbon dioxide, or solid carbon dioxide. The reaction of calcium hydroxide with carbon dioxide may comprise a carbon capture step, which may involve absorbing or separating carbon dioxide from a dilute source of carbon dioxide, such as air, or a source of carbon dioxide which may otherwise be emitted or wasted. In some embodiments, ammonium hydroxide or aqueous ammonia may be employed. In some embodiments, nitrogenous or organic molecules which react with carbon dioxide, such as amines, or ammonia, or imines, or azines, or azides, or ionic liquids, or any combination thereof, may be employed to absorb carbon dioxide. In some embodiments, a physical absorbent, such as water, or selexol, or propylene carbonate, or organic solvent, or methanol, or any combination thereof, may be employed to absorb carbon dioxide. Example Step-by-Step Description of an Example Embodiment: (1) React a material comprising calcium citrate with aqueous sulfur dioxide or sulfurous acid, which may produce a solution comprising at least a portion dissolved calcium bisulfite and dissolved citric acid. (2) Desorb or separate at least a portion of sulfur dioxide from a solution comprising aqueous calcium bisulfite and aqueous citric acid, which may produce gaseous sulfur dioxide, solid calcium sulfite, and liquid solution comprising water, or lean aqueous sulfur dioxide, or lean calcium sulfite, or lean calcium bisulfite, and/or citric acid, or a combination thereof. Desorption may require heat input, or depressurization, or vacuum, or vapor compression, or stripping gas, or a combination thereof. Desorbed sulfur dioxide may be transferred to step ‘(6)’. Solid calcium sulfite and liquid solution may be transferred to step ‘(3)’. In some embodiments, ‘(2)’ and ‘(3)’ may be conducted in the same step. (3) Separate solid calcium sulfite from a liquid solution comprising water, or lean aqueous sulfur dioxide, or lean calcium sulfite, or lean calcium bisulfite, and/or citric acid, or a combination thereof. The present step may involve one or more or a combination of solid-liquid separation processes. Separated solid calcium sulfite may be transferred to step ‘(5)’ and separated liquid solution may be transferred to step ‘(4)’. (4) Separate liquid solution into separated citric acid and separated water. The present step may involve further treatment or purification before or during separation of citric acid from water. The present step may involve water removal, such as mechanical vapor compression distillation, or mechanical vapor re-compression distillation, or evaporation, or distillation, or membrane based process, or crystallization, or other separation processes described herein, or processes for separating citric acid from water in the art, or processes for purifying citric acid or citric acid solutions in the art, or water removal or separation processes described herein, or other water removal or separation processes described in the art, or other separation processes described in the art, or a combination thereof. The present step may produce, for example, solid citric acid, or a citric acid concentrate solution, or a combination thereof. Citric acid may be a product or output from the present step. Separated or recovered water may be transferred to step ‘6’. (5) Decompose solid calcium sulfite into calcium oxide and sulfur dioxide. Calcium oxide may comprise an output of the process, or may be reacted with water to produce calcium hydroxide, or may be transferred to a process to produce calcium citrate or recover or separate citric acid, or a combination thereof. Sulfur dioxide may be transferred to step ‘6’. (6) Absorb sulfur dioxide into a liquid solution comprising water, or lean aqueous sulfur dioxide, or lean calcium sulfite, or lean calcium bisulfite, or a combination thereof to form an aqueous sulfur dioxide solution, or a sulfur dioxide rich solution, or a sulfurous acid solution, or a combination thereof. It may be desirable for the concentration of sulfurous acid or sulfur dioxide in said formed liquid solution to be stoichiometrically at a molar ratio greater than or equal to 1:1 relative to the calcium input, or reacting calcium input, or a combination thereof in step 1 to, for example, enable the formation of soluble calcium bisulfite. Said sulfur dioxide rich solution, or a sulfurous acid solution, or a combination thereof may be transferred to, for example, step 1. Carboxylic Acid Embodiments Description 2 Overview

A process which produces calcium oxide with significantly less or no CO₂ emissions is desirable to significantly reduce or eliminate the emissions from calcium oxide production for various applications, including the production of citric acid. A process which recycles calcium oxide in a citric acid production process to, for example, eliminate or greatly reduce the need for virgin calcium oxide input and sulfuric acid input, is desirable, as such a process has the potential to significantly reduce incremental costs, eliminate or greatly reduce waste products, and significantly reduce or eliminate CO₂ emissions from citric acid production.

Example Summary of Inputs and Outputs of an Example Embodiment Inputs Outputs Calcium Citrate CaO and/or Cement or A Solution Comprising Citric Acid Requiring Recovery/ Separation of Citric Acid (Note: In some embodiments, the Calcium or magnesium may be recycled within a process and may comprise an intermediate rather than an input) Fuel Silicon dioxide or other Option A: Combustible fuel, such as a solid silicon derivative Carbonaceous Fuel and/or Sulfurous or aggregate or a Fuel and/or Hydrogen Fuel and/or combination thereof Nitrogenous Fuel Option B: Electricity, light, or Unreacted materials concentrated solar thermal, or a derivative thereof or similar energy or heat source Sulfurous Salt Waste-Product or Useful Byproduct Calcium Citrate to Calcium Oxide or Cement and Citric Acid (1) Ca₃(C₆H₅O₇)₂.4H₂O(s)+6H₂SO₃(aq)→3Ca(HSO₃)₂(aq)+2C₆H₈O₇(aq)+4H₂O(l or aq) (2) 3Ca(HSO₃)₂(aq)+2C₆H₈O₇(aq)+Heat+3CaSO₃(s)+3H₂O(l)+3SO₂(g)+2C₆H₈O₇(aq) (3) 2C₆H₈O₇(aq)+Heat→2C₆H₈O₇(s) (4) 3CaSO₃(s)+Heat+3CaO(s)+3SO₂(g) (5) 6SO₂(g)+6H₂O(l)+6H₂SO₃(aq) or (1) 2C₆H₈O₇(aq)+3Ca(OH)₂(aq)→Ca₃(C₆H₅O₇)₂.4H₂O(s)+2H₂O(l) (2) Ca₃(C₆H₅O₇)₂.4H₂O(s)+6H₂SO₃(aq)→3Ca(HSO₃)₂(aq)+2C₆H₈O₇(aq)+4H₂O(l or aq) (3) 3Ca(HSO₃)₂(aq)+2C₆H₈O₇(aq)+Heat+3CaSO₃(s)+3H₂O(l)+3SO₂(g)+2C₆H₈O₇(aq) (4) 2C₆H₈O₇(aq)+Heat→2C₆H₈O₇(s) (5) 3CaSO₃(s)+Heat+3CaO(s)+3SO₂(g) (6) 6SO₂(g)+6H₂O(l)+6H₂SO₃(aq) (7) 3CaO(s)+3H₂O→3Ca(OH)₂ (aq or s)+Heat

Note: Calcium oxide may be recycled in a process for producing citric acid. Calcium may comprise an intermediate.

Note: 2C₆H₈O₇(aq) input may comprise a solution comprising a dilute concentration of citric acid or a solution comprising a mixture of citric acid with other solutes, such as sugars. Citric acid may be isolated or removed from said solution by reacting said solution with calcium hydroxide, producing calcium citrate solid precipitate, which is separated from the solution using a solid-liquid separation method, such as filtration, or centrifuge, or a combination thereof, or other method described herein, or other method described in the art.

Example Step-by-Step Description of an Example Embodiment:

(1) React a material comprising calcium citrate with aqueous sulfur dioxide or sulfurous acid, which may produce a solution comprising at least a portion dissolved calcium bisulfite and dissolved citric acid.

(2) Desorb or separate at least a portion of sulfur dioxide from a solution comprising aqueous calcium bisulfite and aqueous citric acid, which may produce gaseous sulfur dioxide, solid calcium sulfite, and liquid solution comprising water, or lean aqueous sulfur dioxide, or lean calcium sulfite, or lean calcium bisulfite, and/or citric acid, or a combination thereof. Desorption may require heat input, or depressurization, or vacuum, or vapor compression, or stripping gas, or a combination thereof. Desorbed sulfur dioxide may be transferred to step ‘(6)’. Solid calcium sulfite and liquid solution may be transferred to step ‘(3)’. In some embodiments, ‘(2)’ and ‘(3)’ may be conducted in the same step. (3) Separate solid calcium sulfite from a liquid solution comprising water, or lean aqueous sulfur dioxide, or lean calcium sulfite, or lean calcium bisulfite, and/or citric acid, or a combination thereof. The present step may involve one or more or a combination of solid-liquid separation processes. Separated solid calcium sulfite may be transferred to step ‘(5)’ and separated liquid solution may be transferred to step ‘(4)’. (4) Separate liquid solution into separated citric acid and separated water. The present step may involve further treatment or purification before or during separation of citric acid from water. The present step may involve water removal, such as mechanical vapor compression distillation, or mechanical vapor re-compression distillation, or evaporation, or distillation, or membrane based process, or crystallization, or other separation processes described herein, or processes for separating citric acid from water in the art, or processes for purifying citric acid or citric acid solutions in the art, or water removal or separation processes described herein, or other water removal or separation processes described in the art, or other separation processes described in the art, or a combination thereof. The present step may produce, for example, solid citric acid, or a citric acid concentrate solution, or a combination thereof. Citric acid may be a product or output from the present step. Separated or recovered water may be transferred to step ‘6’. (5) Decompose solid calcium sulfite into calcium oxide and sulfur dioxide. Calcium oxide may comprise an output of the process, or may be reacted with water to produce calcium hydroxide, or may be transferred to a process to produce calcium citrate or recover or separate citric acid, or a combination thereof. Sulfur dioxide may be transferred to step ‘6’. (6) Absorb sulfur dioxide into a liquid solution comprising water, or lean aqueous sulfur dioxide, or lean calcium sulfite, or lean calcium bisulfite, or a combination thereof to form an aqueous sulfur dioxide solution, or a sulfur dioxide rich solution, or a sulfurous acid solution, or a combination thereof. It may be desirable for the concentration of sulfurous acid or sulfur dioxide in said formed liquid solution to be stoichiometrically at a molar ratio greater than or equal to 1:1 relative to the calcium input, or reacting calcium input, or a combination thereof in step 1 to, for example, enable the formation of soluble calcium bisulfite. Said sulfur dioxide rich solution, or a sulfurous acid solution, or a combination thereof may be transferred to, for example, step 1.

Example Figure Key for FIG. 12 ID Description  1 ‘1’ may comprise calcium citrate or an alkaline-earth - organic acid salt. ‘1’ may comprise an input. ‘1’ may be pulverized.  2 ‘2’ may comprise a process for mixing or reacting or both an input material (such as, for example, ‘1’) with sulfurous acid or a solution comprising dissolved sulfur dioxide. ‘2’ may involve mixing sulfurous acid with a calcium or magnesium - weak acid salt. ‘2’ may involve mixing sulfurous acid with a calcium or magnesium - weak acid salt to form calcium or magnesium sulfite or bisulfite. In the present embodiment, it may be desirable for the molar ratio of sulfur in the sulfurous acid reactant to the calcium and/or magnesium in the input material reactant to be about the same or greater than the molar ratio of sulfur to calcium or magnesium in dissolved calcium bisulfite or magnesium bisulfite. Sulfurous acid reactant in excess of the molar ratio than the molar ratio of sulfur to calcium or magnesium in dissolved calcium bisulfite or magnesium bisulfite may comprise ‘excess’ sulfurous acid. In some embodiments, ‘excess’ sulfurous acid may be desirable in ‘2’ to, for example, improve reaction kinetics or otherwise facilitate the reaction to form calcium bisulfite and/or magnesium bisulfite. ‘2’ may form dissolved calcium bisulfite and/or magnesium bisulfite and a weak acid product. Said weak acid product may comprise an aqueous or dissolved organic acid, which may be at least in part separated from the calcium bisulfite and/or magnesium bisulfite within ‘2’ or in a separate step. For example, said weak acid may comprise aqueous citric acid.  6 ‘6’ may comprise the products from ‘2’. ‘6’ may involve transferring the products from ‘6’ to a process for mixing or reacting or both to a process for desorbing sulfur dioxide and precipitating calcium sulfite, such as ‘7’. In some embodiments, ‘6’ may be heat exchanged with ‘10’ before ‘6’ enters ‘7’.  7 ‘7’ may comprise a process for desorbing sulfur dioxide from a solution comprising bisulfite. ‘7’ may comprise a process for desorbing sulfur dioxide from a solution comprising calcium bisulfite and citric acid. ‘7’ may comprise a process for converting a solution comprising calcium bisulfite and/or excess aqueous sulfur dioxide and/or aqueous citric acid into sulfur dioxide, calcium sulfite precipitate, and aqueous citric acid. The desorption of at least a portion of sulfur dioxide and/or vaporization of at least a portion of water may require heat input, depressurization, or a combination thereof. A portion of water vapor may form and/or may condense with a portion of sulfur dioxide to form aqueous sulfur dioxide or sulfurous acid, which may comprise, for example ‘8’. At least a portion of SO₂(g) may be transferred to a sulfur dioxide absorption process, which may comprise, for example, ‘9’. At least a portion of inputs to ‘7’ may be heat exchanged or counter-current heat exchanged with the outputs of ‘7’, or other liquid or gas or solid streams, or a combination thereof to, for example, minimize the energy required in ‘7’ if, for example, ‘7’ requires heat input, or cooling, or both. ‘7’ may produce a solid-liquid slurry comprising a solid-liquid mixture of calcium sulfite solid and aqueous citric acid liquid.  8 ‘8’ may comprise aqueous sulfur dioxide. ‘8’ may comprise aqueous sulfur dioxide produced from the condensation of water vapor in the presence of sulfur dioxide gas during or after a sulfur dioxide desorption process (for example, ‘7’). In some embodiments, ‘8’ may not be produced or may be minimally produced due to the formation of sulfur dioxide gas with minimal water vapor formation, or minimal water vapor condensation, or both. In some embodiments, ‘8’ may be produced due to, for example, the formation of sulfur dioxide gas formation, or water vapor formation, or water vapor condensation, or a combination thereof. In some embodiments, at least a portion of ‘8’ may be heat exchanged with at least a portion of ‘6’.  9 ‘9’ may comprise gaseous sulfur dioxide. ‘9’ may comprise sulfur dioxide produced from the desorption of sulfur dioxide from a solution comprising calcium bisulfite, or a solution comprising excess sulfur dioxide, or a solution comprising aqueous sulfur dioxide, or a solution comprising citric acid, or a combination thereof. ‘9’ may comprise a portion of water vapor. ‘9’ may undergo pressurization or compression before or during absorption into a solution in, for example, ‘18’. 10 ‘10’ may comprise a solid-liquid mixture. ‘10’ may comprise a solid-liquid mixture comprising calcium sulfite solid and aqueous citric acid, or a SO₂(aq)-lean aqueous solution liquid, or a combination thereof. 11 ‘11’ may comprise a process for solid-liquid separation. ‘11’ may comprise a process to separate at least a portion of solid calcium sulfite from at least a portion of water or a SO₂(aq)-lean aqueous solution liquid. ‘11’ may be conducted under conditions to minimize exposure to air or diatomic oxygen, to, for example, minimize the potential. oxidation of sulfite to sulfate, or other sulfur oxidation, or a combination thereof 12 ‘12’ may comprise calcium sulfite solid. ‘12’ may be transferred under conditions to minimize exposure to air or diatomic oxygen, to, for example, minimize the potential oxidation of sulfite to sulfate, or other sulfur oxidation, or a combination thereof In some embodiments, ‘12’ may be heat exchanged with one or more inputs to ‘7’ to, for example, facilitate heat recovery. In some embodiments, ‘12’ may be sufficiently pulverized or crushed for calcining or other later steps. In some embodiments, ‘12’ may undergo pulverization, or crushing, or grinding to facilitate calcining or to ensure proper dimensions, or material properties, or a combination thereof for, for example, later process steps. 13 ‘13’ may comprise aqueous citric acid and may be a SO₂(aq)-lean aqueous solution liquid. ‘13’ may be transferred under conditions to minimize exposure to air or diatomic oxygen. In some embodiments, ‘13’ may be heat exchanged with one or more inputs to ‘7’ to facilitate heat recovery. In some embodiments, ‘13’ may be heat exchanged with one or more inputs to ‘7’ to, for example, facilitate heat recovery. The concentration of aqueous sulfur dioxide or dissolved sulfur dioxide in ‘13’ may be lower than the concentration of aqueous sulfur dioxide or dissolved sulfur dioxide in ‘17’. 14 ‘14’ may comprise SO₂(g). ‘14’ may comprise a gas mixture comprising at least a portion of SO₂(g) from the calcination, or decomposition, or both of calcium sulfite. ‘14’ may comprise kiln gases from the thermal decomposition or calcination of calcium sulfite, which may comprise sulfur dioxide, or nitrogen, carbon dioxide, or a combination thereof. It may be desirable for ‘14’ to comprise a low concentration, or minimal concentration, or practically no concentration of diatomic oxygen. ‘14’ may be blown, or pressurized, or compressed before at least a portion of sulfur dioxide in ‘14’ is absorbed into an aqueous solution. ‘14’ may comprise a higher partial pressure, or higher concentration, or a combination thereof of sulfur dioxide gas than, for example, ‘16’. In some embodiments, heat may be recovered from ‘14’. In some embodiments, ‘14’ may be cooled. In some embodiments, ‘14’ may be cooled actively, or passively, or a combination thereof. 15 ‘15’ may comprise a gas-liquid contactor, or an absorber, or a combination thereof ‘15’ may comprise a process for absorbing SO₂(g) into an aqueous solution. ‘15’ may comprise a process for absorbing SO₂(g) from a gas comprising at least a portion of SO₂ from gases produced from the decomposition or calcination of calcium sulfite to calcium oxide, or cement, or a combination thereof ‘15’ may involve contacting a gas comprising at least a portion of SO₂ with liquid water or a SO₂(aq)-lean aqueous solution, which may form an aqueous solution with a greater concentration of aqueous sulfur dioxide and a gas comprising a significantly lower concentration of sulfur dioxide, or a gas comprising less sulfur dioxide, or a combination thereof. It may be desirable for ‘15’ to be conducted in a manner which minimizes the exposure of reagents to air or diatomic oxygen. In some embodiments, ‘15’ may be cooled. In some embodiments, ‘15’ may be cooled actively, or passively, or a combination thereof. In some embodiments, ‘15’ may be pressurized, or the internal pressure of ‘15’ may be greater than atmospheric pressure, or a combination thereof. 16 ‘16’ may comprise remaining gases after the absorption of at least a portion of sulfur dioxide from ‘14’. ‘16’ may comprise residual sulfur dioxide, which may comprise sulfur dioxide unabsorbed in ‘15’. Residual sulfur dioxide may be further separated, or scrubbed. For example, at least a portion of residual sulfur dioxide may be removed by a solution comprising sodium bicarbonate, calcium carbonate, or other carbonate or bicarbonate salt. For example, at least a portion of residual sulfur dioxide may be removed by a sulfur dioxide recovery process, such as a reversibly chemical reaction based process, or a non-reversible chemical reaction process, or an oxidation process, or a catalytic process, or a combination thereof. If ‘16’ comprises at least a portion of carbon dioxide, it may be desirable to capture or separate at least a portion of said carbon dioxide in some embodiments. In some embodiments employing the capturing or separating of carbon dioxide from ‘16’, it may be desirable to separate residual sulfur dioxide before, or simultaneous to, or after the capturing or separation of carbon dioxide. 17 ‘17’ may comprise a SO₂(aq) aqueous solution. ‘17’ may be transferred under conditions to minimize exposure to air or diatomic oxygen. The concentration of aqueous sulfur dioxide or dissolved sulfur dioxide in ‘17’ may be lower than the concentration of aqueous sulfur dioxide or dissolved sulfur dioxide in ‘19’. ‘17’ may be cooled before or while being transferred to an absorption step. 18 ‘18’ may comprise a gas-liquid contactor, or an absorber, or a combination thereof. ‘18’ may comprise a process for absorbing SO₂(g) into an aqueous solution. ‘18’ may comprise a process for absorbing SO₂(g) from a gas comprising at least a portion of SO₂(g) from gases produced from the desorption of sulfur dioxide gas from a solution comprising at least a portion of calcium bisulfite, or aqueous sulfur dioxide, or a combination thereof. ‘18’ may involve contacting a gas comprising at least a portion of SO₂ with a SO₂(aq) aqueous solution, which may form an aqueous solution with a greater concentration of aqueous sulfur dioxide. It may be desirable for ‘18’ to be conducted in a manner which minimizes the exposure of reagents to air or diatomic oxygen. In some embodiments, ‘18’ may be cooled. In some embodiments, ‘18’ may be cooled actively, or passively, or a combination thereof. In some embodiments, ‘18’ may be pressurized, or the internal pressure of ‘18’ may be greater than atmospheric pressure, or a combination thereof. 19 ‘19’ may comprise a SO₂(aq) aqueous solution. ‘19’ may be transferred under conditions to minimize exposure to air or diatomic oxygen. The concentration of aqueous sulfur dioxide or dissolved sulfur dioxide in ‘19’ may be greater than the concentration of aqueous sulfur dioxide or dissolved sulfur dioxide in ‘17’. In some embodiments, at least a portion of ‘19’ may be heat exchanged with at least a portion of ‘3’. In some embodiments, ‘19’ may contain aqueous sulfur dioxide in an amount equal to or greater than a molar ratio of 2:1 sulfur:calcium relative to the calcium in ‘1’. In some embodiments, ‘19’ + ‘8’ may contain aqueous sulfur dioxide in an amount equal to or greater than a molar ratio of 2:1 sulfur:calcium relative to the calcium in ‘1’. 20 ‘20’ may comprise a process for calcining, or thermal decomposition, or gas forming reaction, or a combination thereof. ‘20’ may comprise a process for converting calcium sulfite into calcium oxide and sulfur dioxide. ‘20’ may involve converting calcium sulfite and cement manufacturing inputs, such as clay, shale, sand, iron ore, bauxite, fly ash, and slag, into cement, or cement clinker, into cement, or cement clinker, or sulfur dioxide, or a combination thereof. ‘20’ may comprise a kiln or calcining process. ‘20’ may be powered by one or more or a combination of heat sources described herein or heat sources known in the art. ‘20’ may be designed to operate to minimize exposure of reagents to diatomic oxygen or air. ‘20’ may comprise a single step process. ‘20’ may comprise a multi-step process. ‘20’ may comprise a process to produce calcium oxide. ‘20’ may comprise a process to produce calcium oxide, then convert said calcium oxide into cement in a reaction with cement manufacturing inputs, such as clay, shale, sand, iron ore, bauxite, fly ash, and slag, into cement, or cement clinker. ‘20’ may comprise a process to produce cement in a reaction with cement manufacturing inputs, such as clay, shale, sand, iron ore, bauxite, fly ash, and slag, into cement, or cement clinker. ‘20’ may comprise a process for producing sulfur dioxide. ‘20’ may comprise a process for producing calcium oxide from calcium sulfite. 30 ‘30’ may comprise a gas. ‘30’ may comprise air. ‘30’ may comprise a recirculated gas. ‘30’ may comprise a combination of gases or a mixture of gases or a gas comprising multiple components. ‘30’ may comprise oxygen. ‘30’ may comprise nitrogen. 31 ‘31’ may comprise energy input. ‘31’ may comprise energy input to power a calciner, or a kiln, or a combination thereof. ‘31’ may comprise energy input to power the conversion of calcium sulfite to calcium oxide and/or cement and/or sulfur dioxide. ‘31’ may comprise, including, but not limited to, one or more or a combination of the following: heat, or fuel, or electricity, or light, or radiative heating, or inductive heating, or heat transfer medium. 33 ‘33’ may comprise a process for separating or concentrating a dissolved acid, or a dissolved organic acid, such as citric acid. ‘33’ may comprise a process for removing water from citric acid, or concentrating citric acid, or producing solid citric acid, or crystalizing citric acid, or a water removal process, or a purification process, or a combination thereof. ‘33’ may produce separated water and a solid citric acid product. ‘33’ may further separate residual sulfur dioxide, if any, for a solution. If any, said sulfur dioxide may be transferred to an absorption step, such as ‘15’ or ‘18’, or a step to re- incorporate said sulfur dioxide into the process or solution, or a combination thereof. 34 ‘34’ may comprise water lean in sulfur dioxide or practically free of sulfur dioxide and/ or lean in citric acid or practically free in citric acid. ‘34’ may be transferred from a process for separating citric acid to an absorption step, wherein, for example, ‘34’ may comprise an absorption solution input to absorb sulfur dioxide gas. 35 ‘35’ may comprise separated or isolated citric acid, or other separated acid, or other separated organic acid, or a combination thereof. ‘35’ may comprise citric acid which may be an output of the process. ‘35’ may undergo further treatment or processing.

Example Exemplary Embodiments

Organic Acid, or Citric Acid, or Soluble Anion or Soluble Acid

1. A process for producing an alkaline-earth oxide and carboxylic acid from an alkaline earth cation-carboxylic acid anion salt comprising:

-   -   Reacting an alkaline-earth cation-carboxylic acid anion salt         with aqueous sulfur dioxide to produce aqueous         alkaline-earth-bisulfite and aqueous carboxylic acid     -   Desorbing sulfur dioxide from said aqueous         alkaline-earth-bisulfite and aqueous carboxylic acid solution to         produce alkaline-earth-sulfite solid and aqueous carboxylic acid         solution     -   Separating said alkaline-earth-sulfite solid from said aqueous         carboxylic acid solution     -   Calcining said alkaline-earth-sulfite solid to produce         alkaline-earth-oxide or cement         2. The process of example embodiment 1 wherein said         alkaline-earth comprises calcium         3. The process of example embodiment 1 wherein said         alkaline-earth comprises magnesium         4. The process of example embodiment 1 wherein said carboxylic         acid comprises citric acid         5. The process of example embodiment 1 wherein said carboxylic         acid solution is separated into isolated carboxylic acid and         water         6. The process of example embodiment 5 wherein said water is         employed to absorb sulfur dioxide to regenerate the aqueous         sulfur dioxide         7. The process of example embodiment 1 wherein said desorbed         sulfur dioxide is absorbed in water to produce aqueous sulfur         dioxide         8. The process of example embodiment 1 wherein said calcining of         calcium sulfite produces sulfur dioxide         9. The process of example embodiment 8 wherein said sulfur         dioxide is absorbed in water to produce aqueous sulfur dioxide         10. The process of example embodiment 1 wherein said         alkaline-earth-oxide is reacted with water to produce         alkaline-earth-hydroxide         11. The process of example embodiment 10 wherein said reaction         produces heat and said heat is used in one or more processes         12. The process of example embodiment 10 wherein said         alkaline-earth-hydroxide is reacted with a solution comprising         at least a portion a carboxylic acid; and forming at least a         portion of alkaline-earth cation-carboxylic acid anion salt         13. The process of example embodiment 12 wherein said         alkaline-earth cation-carboxylic acid anion salt comprises at         least a portion a solid         14. The process of example embodiment 13 wherein said         alkaline-earth cation-carboxylic acid anion salt is separated         using a solid-liquid separation process         15. The process of example embodiment 1 wherein said separating         comprises a solid-liquid separation process         16. The process of example embodiment 1 wherein the process is         conducted in the presence of a low diatomic oxygen environment         17. The process of example embodiment 1 is conducted under         conditions to substantially prevent the formation of sulfate         18. The process of example embodiment 1 wherein said         alkaline-earth-hydroxide is employed to produce precipitated         alkaline-earth-carbonate         19. The process of example embodiment 18 wherein said         precipitate alkaline-earth-carbonate comprises calcium         carbonate, or magnesium carbonate, or both         20. The process of example embodiment 10 wherein said         alkaline-earth-hydroxide forms a solution comprising dissolved         aqueous alkaline-earth-hydroxide         21. The process of example embodiment 12 wherein said         alkaline-earth-hydroxide comprises an aqueous solution of         dissolved alkaline-earth-hydroxide         22. The process of example embodiment 12 wherein said         alkaline-earth-hydroxide comprises calcium hydroxide         23. The process of example embodiment 5 wherein said separating         produces at least a portion of sulfur dioxide         24. The process of example embodiment 5 wherein said water         comprises at least a portion of aqueous sulfur dioxide         25. The process of example embodiment 22 wherein said sulfur         dioxide comprises gaseous sulfur dioxide         26. The process of example embodiment 24 wherein at least a         portion of said gaseous sulfur dioxide is absorbed to form at         least a portion of aqueous sulfur dioxide         27. The process of example embodiment 11 wherein said one or         more processes include desorbing sulfur dioxide, or separating         water, or both         28. A process for producing calcium oxide and carboxylic acid         from a calcium cation-carboxylic acid anion salt comprising:     -   Reacting a calcium cation-carboxylic acid anion salt with         aqueous sulfur dioxide to produce aqueous calcium bisulfite and         aqueous carboxylic acid     -   Desorbing sulfur dioxide from said aqueous calcium bisulfite and         aqueous carboxylic acid solution to produce calcium sulfite         solid and aqueous carboxylic acid solution     -   Separating said calcium sulfite solid from said aqueous         carboxylic acid solution     -   Calcining said calcium sulfite solid to produce calcium oxide or         cement         29. A process for producing calcium oxide and citric acid from         calcium citrate comprising:     -   Reacting calcium citrate with aqueous sulfur dioxide to produce         aqueous calcium bisulfite and aqueous citric acid     -   Desorbing sulfur dioxide from said aqueous calcium bisulfite and         aqueous citric acid solution to produce calcium sulfite solid         and aqueous citric acid solution     -   Separating said calcium sulfite solid from said aqueous citric         acid solution     -   Calcining said calcium sulfite solid to produce calcium oxide or         cement         Organic Acid, or Citric Acid, or Soluble Anion or Soluble Acid         1. A process for producing a metal oxide and carboxylic acid         from metal cation-carboxylic acid anion salt comprising:     -   Reacting a metal-carboxylic acid anion salt with aqueous sulfur         dioxide to produce aqueous metal bisulfite and aqueous         carboxylic acid     -   Desorbing sulfur dioxide from said aqueous metal bisulfite and         aqueous carboxylic acid solution to produce metal sulfite solid         and aqueous carboxylic acid solution     -   Separating said metal sulfite solid from said aqueous carboxylic         acid solution     -   Calcining said metal sulfite solid to produce metal oxide         2. The process of example embodiment 1 wherein said metal         comprises calcium, or magnesium, or both         3. The process of example embodiment 1 wherein said metal         comprises iron, or manganese, or both         4. The process of example embodiment 1 wherein said carboxylic         acid comprises citric acid         5. The process of example embodiment 1 wherein said carboxylic         acid solution is separated into isolated carboxylic acid and         water         6. The process of example embodiment 5 wherein said water is         employed to absorb sulfur dioxide to regenerate the aqueous         sulfur dioxide         7. The process of example embodiment 1 wherein said desorbed         sulfur dioxide is absorbed in water to produce aqueous sulfur         dioxide         8. The process of example embodiment 1 wherein said calcining of         metal sulfite produces sulfur dioxide         9. The process of example embodiment 8 wherein said sulfur         dioxide is absorbed in water to produce aqueous sulfur dioxide         10. The process of example embodiment 1 wherein said metal oxide         is reacted with water to produce a metal hydroxide         11. The process of example embodiment 10 wherein said reaction         produces heat and said heat is used in one or more processes         12. The process of example embodiment 10 wherein said metal         hydroxide is reacted with a solution comprising at least a         portion a carboxylic acid; and     -   forming at least a portion of metal-carboxylic acid salt         13. The process of example embodiment 12 wherein said         metal-carboxylic acid salt comprises at least a portion a solid         14. The process of example embodiment 13 wherein said         metal-carboxylic acid salt is separated using a solid-liquid         separation process         15. The process of example embodiment 1 wherein said separating         comprises a solid-liquid separation process         16. The process of example embodiment 1 wherein the process is         conducted in the presence of a low diatomic oxygen environment         17. The process of example embodiment 1 is conducted under         conditions to substantially prevent the formation of sulfate         18. The process of example embodiment 1 wherein said         metal-hydroxide is employed to produce precipitated         metal-carbonate         19. The process of example embodiment 18 wherein said         precipitate metal-carbonate comprises calcium carbonate, or         magnesium carbonate, or iron carbonate, or manganese carbonate,         or a combination thereof         20. The process of example embodiment 10 wherein said         metal-hydroxide forms a solution comprising dissolved aqueous         metal-hydroxide         21. The process of example embodiment 12 wherein said         metal-hydroxide comprises an aqueous solution of dissolved         metal-hydroxide         22. The process of example embodiment 12 wherein said         metal-hydroxide comprises calcium hydroxide         23. The process of example embodiment 5 wherein said separating         produces at least a portion of sulfur dioxide         24. The process of example embodiment 5 wherein said water         comprises at least a portion of aqueous sulfur dioxide         25. The process of example embodiment 22 wherein said sulfur         dioxide comprises gaseous sulfur dioxide         26. The process of example embodiment 24 wherein at least a         portion of said gaseous sulfur dioxide is absorbed to form at         least a portion of aqueous sulfur dioxide         27. The process of example embodiment 11 wherein said one or         more processes include desorbing sulfur dioxide, or separating         water, or both         28. A process for producing metal oxide and carboxylic acid from         a metal cation-carboxylic acid anion salt comprising:     -   Reacting a metal cation-carboxylic acid anion salt with aqueous         sulfur dioxide to produce aqueous metal bisulfite and aqueous         carboxylic acid     -   Desorbing sulfur dioxide from said aqueous metal bisulfite and         aqueous carboxylic acid solution to produce metal sulfite solid         and aqueous carboxylic acid solution     -   Separating said metal sulfite solid from said aqueous carboxylic         acid solution     -   Calcining said metal sulfite solid to produce calcium oxide or         cement         29. A process for producing metal oxide and citric acid from         calcium citrate comprising:     -   Reacting metal citrate with aqueous sulfur dioxide to produce         aqueous metal bisulfite and aqueous citric acid     -   Desorbing sulfur dioxide from said aqueous metal bisulfite and         aqueous citric acid solution to produce metal sulfite solid and         aqueous citric acid solution     -   Separating said metal sulfite solid from said aqueous citric         acid solution     -   Calcining said metal sulfite solid to produce metal oxide         1. A process for producing an alkaline-earth oxide and a         carboxylic acid from an alkaline earth cation-carboxylic acid         anion salt wherein the process comprises:

reacting an alkaline-earth cation-carboxylic acid anion salt with aqueous sulfur dioxide to produce aqueous alkaline-earth-bisulfite and aqueous carboxylic acid solution;

desorbing sulfur dioxide from said aqueous alkaline-earth-bisulfite and aqueous carboxylic acid solution to produce alkaline-earth-sulfite solid and aqueous carboxylic acid solution;

separating said alkaline-earth-sulfite solid from said aqueous carboxylic acid solution; and

calcining said alkaline-earth-sulfite solid to produce alkaline-earth-oxide, cement, or a combination thereof.

2. The process of example exemplary embodiment 1 wherein said alkaline-earth cation comprises calcium cation.

3. The process of example exemplary embodiment 1 wherein said alkaline-earth cation comprises magnesium cation.

4. The process of example exemplary embodiment 1 wherein said carboxylic acid anion salt comprises citric acid anion salt.

5. The process of example exemplary embodiment 1 which further comprises separating aqueous carboxylic acid solution into isolated carboxylic acid and water.

6. The process of example exemplary embodiment 5 which further comprises absorbing sulfur dioxide with said water to generate aqueous sulfur dioxide for the reacting step.

7. The process of example exemplary embodiment 1 which further comprises absorbing said desorbed sulfur dioxide in water to produce aqueous sulfur dioxide.

8. The process of example exemplary embodiment 1 wherein said calcining said alkaline-earth-sulfite solid produces sulfur dioxide.

9. The process of example exemplary embodiment 8 which further comprises absorbing said sulfur dioxide in water to produce aqueous sulfur dioxide.

10. The process of example exemplary embodiment 1 which further comprises reacting said alkaline-earth-oxide with water to produce alkaline-earth-hydroxide.

11. The process of example exemplary embodiment 10 wherein said reacting produces heat and wherein said heat is used in the process.

12. The process of example exemplary embodiment 10 which further comprises reacting said alkaline-earth-hydroxide with a solution comprising a carboxylic acid to form alkaline-earth cation-carboxylic acid anion salt.

13. The process of example exemplary embodiment 12 wherein at least a portion of said alkaline-earth cation-carboxylic acid anion salt is a solid.

14. The process of example exemplary embodiment 13 which further comprises separating said alkaline-earth cation-carboxylic acid anion salt using solid-liquid separation.

15. The process of example exemplary embodiment 1 wherein said separating comprises a solid-liquid separation step.

16. The process of example exemplary embodiment 1 wherein the process is conducted in the presence of a low diatomic oxygen environment.

17. The process of example exemplary embodiment 1 wherein the process is conducted under conditions to substantially prevent the formation of sulfate.

18. The process of example exemplary embodiment 1 which further comprises producing a precipitated alkaline-earth-carbonate from said alkaline-earth-hydroxide.

19. The process of example exemplary embodiment 18 wherein said precipitated alkaline-earth-carbonate comprises calcium carbonate, magnesium carbonate, or both.

20. The process of example exemplary embodiment 10 wherein said alkaline-earth-hydroxide is dissolved in water.

21. The process of example exemplary embodiment 12 wherein said alkaline-earth-hydroxide is dissolved in water.

22. The process of example exemplary embodiment 12 wherein said alkaline-earth-hydroxide comprises calcium hydroxide.

23. The process of example exemplary embodiment 5 wherein said isolated water comprises dissolved sulfur dioxide.

24. The process of example exemplary embodiment 22 which further comprises separating sulfur dioxide from the isolated water.

25. The process of example exemplary embodiment 22 wherein said sulfur dioxide comprises gaseous sulfur dioxide.

26. The process of example exemplary embodiment 24 wherein at least a portion of said gaseous sulfur dioxide is absorbed to form at least a portion of aqueous sulfur dioxide.

27. The process of example exemplary embodiment 10 wherein said reacting produces heat and wherein said heat is used desorb sulfur dioxide, separate water, or both.

28. A process for producing calcium oxide and carboxylic acid from a calcium cation-carboxylic acid anion salt wherein the process comprises:

reacting a calcium cation-carboxylic acid anion salt with aqueous sulfur dioxide to produce aqueous calcium bisulfite and aqueous carboxylic acid;

desorbing sulfur dioxide from said aqueous calcium bisulfite and aqueous carboxylic acid solution to produce calcium sulfite solid and aqueous carboxylic acid solution;

separating said calcium sulfite solid from said aqueous carboxylic acid solution; and calcining said calcium sulfite solid to produce calcium oxide, cement, or a combination thereof.

29. A process for producing calcium oxide and citric acid from calcium citrate wherein the process comprises:

reacting calcium citrate with aqueous sulfur dioxide to produce aqueous calcium bisulfite and aqueous citric acid;

desorbing sulfur dioxide from said aqueous calcium bisulfite and aqueous citric acid solution to produce calcium sulfite solid and aqueous citric acid solution;

separating said calcium sulfite solid from said aqueous citric acid solution; and calcining said calcium sulfite solid to produce calcium oxide, cement, or a combination thereof.

Notes

-   -   Note: Some embodiments may involve reacting a material         comprising calcium and/or magnesium with supercritical, or         liquid, or gaseous, or any combination thereof sulfur dioxide to         form calcium sulfite and/or magnesium sulfite, then contacting         at least a portion of the formed calcium sulfite and/or         magnesium sulfite with water to form at least a portion of         dissolve magnesium sulfite.     -   Note: MgCa(CO₃)₂(s) may comprise a solid comprising a mixture of         calcium and magnesium salts. MgCa(CO₃)₂(s) may comprise, for         example, including, but not limited to, limestone or dolomite.         Alternatively, or additionally, MgCa(CO₃)₂(s) may comprise a         portion of magnesium silicate or magnesium aluminate or         magnesium ferrate. Alternatively, or additionally, MgCa(CO₃)₂(s)         may comprise a portion of calcium silicate or calcium aluminate         or calcium ferrate.     -   Note: In some embodiments, a solvent other than or in addition         to water may be employed. For example, an organic solvent or         inorganic solvent may be present in solution. For example, a         glycol, or an alcohol, or a sugar alcohol may be present. For         example, an organic solvent or a solvent other than water. For         example, ammonia or urea may be present in solution.     -   Note: Concentration of aqueous magnesium sulfite in a solution         comprising aqueous magnesium sulfite may be greater than or         equal to one or more or a combination of the following: 0.025         g/L, or 0.05 g/L, or 0.1 g/L, or 0.2 g/L, or 0.3 g/L, 0.4 g/L,         or 0.5 g/L, or 0.6 g/L, or 0.7 g/L, or 0.8 g/L, or 0.9 g/L, or         1.0 g/L, or 1.1 g/L, or 1.2 g/L, or 1.3 g/L, or 1.4 g/L, or 1.5         g/L, or 1.6 g/L, or 1.7 g/L, or 1.8 g/L, or 1.9 g/L, or 2 g/L     -   Note: ‘g/L’ may comprise grams of solute per liter of solution.         For example, 1 g/L of magnesium sulfate may comprise a solution         with 1 gram of dissolved magnesium sulfite per liter of total         solution.     -   Note: Temperature of at least a portion of concentrating with         reverse osmosis or forward osmosis or both may be greater than         or equal to one or more or a combination of the following: 0°         C., or 5° C., or 10° C., or 15° C., or 20° C., or 25° C., or 30°         C., or 35° C., or 40° C., or 45° C., or 50° C., or 55° C., or         60° C., or 65° C., or 70° C., or 75° C., or 80° C., or 85° C.,         or 90° C., or 95° C., or 100° C., or 105° C., or 110° C., or         115° C.     -   Note: Temperature of calcining at least a portion of calcium         sulfite, or magnesium sulfite, or both may be greater than or         equal to one or more or a combination of the following: 500° C.,         or 550° C., or 600° C., or 650° C., or 700° C., or 750° C., or         775° C., or 800° C., or 825° C., or 850° C., or 875° C., or 900°         C.     -   Note: Temperature of drying or dehydrating or both may be less         than or equal to one or more or a combination of the following:         800° C., or 750° C., or 700° C., or 650° C., or 600° C., or 550°         C., or 500° C., or 450° C., or 400° C., or 350° C., or 300° C.,         or 250° C., or 200° C., or 150° C., or 100° C.     -   Note: The partial pressure of captured carbon dioxide produced         by one or more or a combination of embodiments may be greater         than or equal to one or more or a combination of the following:         0.05 atm, or 0.1 atm, or 0.2 atm, or 0.3 atm, or 0.4 atm, or 0.5         atm, or 0.6 atm, or 0.7 atm, or 0.8 atm, or 0.9 atm, or 1 atm,         or 1.1 atm, or 1.2 atm, or 1.3 atm, or 1.4 atm, or 1.5 atm, or         1.6 atm, or 1.7 atm, or 1.8 atm, or 1.9 atm, or 2.0 atm, or 2.25         atm, or 2.5 atm, or 2.75 atm, or 3 atm, or 4 atm, or 5 atm, or 6         atm, or 7 atm, or 8 atm, or 9 atm, or 10 atm, or 12.5 atm, or 15         atm, or 17.5 atm, or 20 atm, or 25 atm, or 30 atm, or 35 atm, or         40 atm, or 45 atm, or 50 atm     -   Note: The concentration of captured carbon dioxide produced by         the process may comprise a volume percent concentration of         carbon dioxide which may include, but is not limited to, greater         than, or equal to, one or more or a combination of the         following: 50%, or 50.5%, or 51%, or 51.5%, or 52%, or 52.5%, or         53%, or 53.5%, or 54%, or 54.5%, or 55%, or 55.5%, or 56%, or         56.5%, or 57%, or 57.5%, or 58%, or 58.5%, or 59%, or 59.5%, or         60%, or 60.5%, or 61%, or 61.5%, or 62%, or 62.5%, or 63%, or         63.5%, or 64%, or 64.5%, or 65%, or 65.5%, or 66%, or 66.5%, or         67%, or 67.5%, or 68%, or 68.5%, or 69%, or 69.5%, or 70%, or         70.5%, or 71%, or 71.5%, or 72%, or 72.5%, or 73%, or 73.5%, or         74%, or 74.5%, or 75%, or 75.5%, or 76%, or 76.5%, or 77%, or         77.5%, or 78%, or 78.5%, or 79%, or 79.5%, or 80%, or 80.5%, or         81%, or 81.5%, or 82%, or 82.5%, or 83%, or 83.5%, or 84%, or         84.5%, or 85%, or 85.5%, or 86%, or 86.5%, or 87%, or 87.5%, or         88%, or 88.5%, or 89%, or 89.5%, or 90%, or 90.5%, or 91%, or         91.5%, or 92%, or 92.5%, or 93%, or 93.5%, or 94%, or 94.5%, or         95%, or 95.5%, or 96%, or 96.5%, or 97%, or 97.5%, or 98%, or         98.5%, or 99%, or 99.5%     -   Note: The concentration of captured carbon dioxide produced by         the process may comprise a volume percent concentration of         carbon dioxide which may include, greater than, or equal to, one         or more or a combination of the following: 0.5%, or 1%, or 1.5%,         or 2%, or 2.5%, or 3%, or 3.5%, or 4%, or 4.5%, or 5%, or 5.5%,         or 6%, or 6.5%, or 7%, or 7.5%, or 8%, or 8.5%, or 9%, or 9.5%,         or 10%, or 10.5%, or 11%, or 11.5%, or 12%, or 12.5%, or 13%, or         13.5%, or 14%, or 14.5%, or 15%, or 15.5%, or 16%, or 16.5%, or         17%, or 17.5%, or 18%, or 18.5%, or 19%, or 19.5%, or 20%, or         20.5%, or 21%, or 21.5%, or 22%, or 22.5%, or 23%, or 23.5%, or         24%, or 24.5%, or 25%, or 25.5%, or 26%, or 26.5%, or 27%, or         27.5%, or 28%, or 28.5%, or 29%, or 29.5%, or 30%, or 30.5%, or         31%, or 31.5%, or 32%, or 32.5%, or 33%, or 33.5%, or 34%, or         34.5%, or 35%, or 35.5%, or 36%, or 36.5%, or 37%, or 37.5%, or         38%, or 38.5%, or 39%, or 39.5%, or 40%, or 40.5%, or 41%, or         41.5%, or 42%, or 42.5%, or 43%, or 43.5%, or 44%, or 44.5%, or         45%, or 45.5%, or 46%, or 46.5%, or 47%, or 47.5%, or 48%, or         48.5%, or 49%, or 49.5%, or 50%, or 50.5%, or 51%, or 51.5%, or         52%, or 52.5%, or 53%, or 53.5%, or 54%, or 54.5%, or 55%, or         55.5%, or 56%, or 56.5%, or 57%, or 57.5%, or 58%, or 58.5%, or         59%, or 59.5%, or 60%, or 60.5%, or 61%, or 61.5%, or 62%, or         62.5%, or 63%, or 63.5%, or 64%, or 64.5%, or 65%, or 65.5%, or         66%, or 66.5%, or 67%, or 67.5%, or 68%, or 68.5%, or 69%, or         69.5%, or 70%, or 70.5%, or 71%, or 71.5%, or 72%, or 72.5%, or         73%, or 73.5%, or 74%, or 74.5%, or 75%, or 75.5%, or 76%, or         76.5%, or 77%, or 77.5%, or 78%, or 78.5%, or 79%, or 79.5%, or         80%, or 80.5%, or 81%, or 81.5%, or 82%, or 82.5%, or 83%, or         83.5%, or 84%, or 84.5%, or 85%, or 85.5%, or 86%, or 86.5%, or         87%, or 87.5%, or 88%, or 88.5%, or 89%, or 89.5%, or 90%, or         90.5%, or 91%, or 91.5%, or 92%, or 92.5%, or 93%, or 93.5%, or         94%, or 94.5%, or 95%, or 95.5%, or 96%, or 96.5%, or 97%, or         97.5%, or 98%, or 98.5%, or 99%, or 99.5%, or 100%     -   Note: ‘A portion’: A portion may comprise a part of a stream or         material, or all of a stream or material. A portion may include,         but is not limited to, less than, or greater than, or equal to,         one or more or a combination of the following: 0%, or 0.5%, or         1%, or 1.5%, or 2%, or 2.5%, or 3%, or 3.5%, or 4%, or 4.5%, or         5%, or 5.5%, or 6%, or 6.5%, or 7%, or 7.5%, or 8%, or 8.5%, or         9%, or 9.5%, or 10%, or 10.5%, or 11%, or 11.5%, or 12%, or         12.5%, or 13%, or 13.5%, or 14%, or 14.5%, or 15%, or 15.5%, or         16%, or 16.5%, or 17%, or 17.5%, or 18%, or 18.5%, or 19%, or         19.5%, or 20%, or 20.5%, or 21%, or 21.5%, or 22%, or 22.5%, or         23%, or 23.5%, or 24%, or 24.5%, or 25%, or 25.5%, or 26%, or         26.5%, or 27%, or 27.5%, or 28%, or 28.5%, or 29%, or 29.5%, or         30%, or 30.5%, or 31%, or 31.5%, or 32%, or 32.5%, or 33%, or         33.5%, or 34%, or 34.5%, or 35%, or 35.5%, or 36%, or 36.5%, or         37%, or 37.5%, or 38%, or 38.5%, or 39%, or 39.5%, or 40%, or         40.5%, or 41%, or 41.5%, or 42%, or 42.5%, or 43%, or 43.5%, or         44%, or 44.5%, or 45%, or 45.5%, or 46%, or 46.5%, or 47%, or         47.5%, or 48%, or 48.5%, or 49%, or 49.5%, or 50%, or 50.5%, or         51%, or 51.5%, or 52%, or 52.5%, or 53%, or 53.5%, or 54%, or         54.5%, or 55%, or 55.5%, or 56%, or 56.5%, or 57%, or 57.5%, or         58%, or 58.5%, or 59%, or 59.5%, or 60%, or 60.5%, or 61%, or         61.5%, or 62%, or 62.5%, or 63%, or 63.5%, or 64%, or 64.5%, or         65%, or 65.5%, or 66%, or 66.5%, or 67%, or 67.5%, or 68%, or         68.5%, or 69%, or 69.5%, or 70%, or 70.5%, or 71%, or 71.5%, or         72%, or 72.5%, or 73%, or 73.5%, or 74%, or 74.5%, or 75%, or         75.5%, or 76%, or 76.5%, or 77%, or 77.5%, or 78%, or 78.5%, or         79%, or 79.5%, or 80%, or 80.5%, or 81%, or 81.5%, or 82%, or         82.5%, or 83%, or 83.5%, or 84%, or 84.5%, or 85%, or 85.5%, or         86%, or 86.5%, or 87%, or 87.5%, or 88%, or 88.5%, or 89%, or         89.5%, or 90%, or 90.5%, or 91%, or 91.5%, or 92%, or 92.5%, or         93%, or 93.5%, or 94%, or 94.5%, or 95%, or 95.5%, or 96%, or         96.5%, or 97%, or 97.5%, or 98%, or 98.5%, or 99%, or 99.5%, or         100%     -   Note: Calcining may involve thermally decomposing calcium         sulfite and/or magnesium sulfite into calcium oxide and/or         magnesium oxide. Calcining may involve thermally decomposing         calcium carbonate and/or magnesium carbonate into calcium oxide         and/or magnesium oxide.     -   Note: In some embodiments, calcium sulfite and magnesium sulfite         may be calcined separately. For example, in some embodiments,         calcium sulfite may be calcined in a separate kiln than         magnesium sulfite. For example, in some embodiments, calcium         sulfite may be calcined in the same kiln as magnesium sulfite,         although in different locations within the same kiln. For         example, in some embodiments, calcium sulfite may be calcined in         the same kiln as magnesium sulfite, although at different times.     -   Note: In some embodiments, calcium sulfite and magnesium sulfite         may be calcined in the same kiln. For example, a material may         comprise both calcium sulfite and magnesium sulfite, and said         material comprising both calcium sulfite and magnesium sulfite         may be calcined. For example, a separate calcium sulfite and         magnesium sulfite may be mixed and may be calcined in the same         kiln as a mixture.     -   Note: Some embodiments may involve using an input material         comprising a salt of calcium and/or magnesium and a weak acid,         wherein said weak acid comprises a weak acid anion other than a         carbon dioxide derivative, or other than a carbonate. For         example, said weak acid anion other than a carbon dioxide         derivative may comprise, including, but not limited to, one or         more or a combination of the following: a sulfide, or silicon         derivative, or silicate, or aluminate, or ferrate, or ferrite,         or iron, or zinc, or aluminum, or manganese, or copper, or a         combination thereof.         Additional Notes     -   Note: In some embodiments, a material comprising calcium and/or         magnesium may comprise calcium silicate or magnesium silicate or         both. In some embodiments, a material comprising calcium and/or         magnesium may comprise, for example, including, but not limited         to, cement, or concrete, or waste concrete, or steel slag, or         iron slag, or slag, or a combination thereof.     -   Note: If non-calcium of non-magnesium metals dissolve or react         with SO2 or sulfurous acid, these minerals may be separated         before or after separation of calcium sulfite or magnesium         sulfite or both. If these non-calcium of non-magnesium metal         salts are still dissolved, they may be separated by         precipitation, or systems and/or methods for zero liquid         discharge, or a combination thereof.     -   Note: Employ the calcium oxide produced by the present invention         as an input to the Solvay to make reduced CO₂ emissions sodium         carbonate and sodium bicarbonate. Calcium oxide is used in the         Solvay process to remove chloride from ammonium chloride.     -   Note: Some embodiments may employ high temperature steam in the         calcination process. In some embodiments, it may be desirable         for the temperature of the steam to be greater than the         decomposition temperature or decomposition temperature range of         calcium hydroxide. At least a portion of the steam may be         condensed after forming a mixture with sulfur dioxide. If steam         is employed, it must be contacted at a temperature greater than         the decomposition temperature of calcium hydroxide.     -   Note: Sulfur dioxide may be separated or recovered by cryogenic         separation, or freezing separation, or liquification separation,         or condensing separation, or deposition separation, or a         combination thereof. The resulting liquid or solid or         supercritical SO₂ may be added to water or sulfurous acid         solution to form or maintain concentrated or ‘excess’ sulfurous         acid. Alternatively or additionally, the resulting liquid or         solid or supercritical SO₂ may be reacted with directly with the         material comprising calcium and/or magnesium.     -   Note: Thermally decompose calcium sulfite in an electric kiln     -   Note: Thermally decompose calcium sulfite in a natural gas or         coal or both kiln.     -   Note: Thermally decompose calcium sulfite using a hydrogen fuels         system. If hydrogen is used for heat, there may be no CO2         emissions in the end to end process. Also, green hydrogen can be         produced from solar energy and stored, eliminating the challenge         of solar intermittency. Alternatively or additionally, hydrogen         may be blue hydrogen, or hydrogen from natural gas, where the         carbon or CO2 is removed from the natural gas to produce         hydrogen before hydrogen is burned. Alternatively, a process may         employ a combination of blue hydrogen (during the night) and         solar electricity (during the day).     -   Note: Some embodiments may employ a hydrogen powered kiln. In         some embodiments, the resulting water vapor may be condensed to         form sulfurous acid. In some embodiments where combustion is         employed to power the calcining and said combustion forms water,         it may be desirable for a portion of said water to be condensed         to form at least a portion of aqueous sulfur dioxide.     -   Note: ‘Aqueous sulfur dioxide’ and ‘sulfurous acid’ may be         employed interchangeably     -   Note: Recovery heat form hydrating calcium oxide to calcium         hydroxide to provide heat or steam or both for applications         requiring heat     -   Note: Remaining flue gas after most or all SO2 is removed or         recovered may comprise at least a portion CO2.     -   Note: Flue gas or CO2 from the flue gas may be employed as a CO2         input or CO2 source for a Solvay process to produce Sodium         Bicarbonate or Sodium Carbonate. The Solvay process calcium         oxide will be sourced from the present invention.     -   Note: Flue gas CO2 may be concentrated with pressure swing         absorption or pressure swing adsorption or gas membrane or both,         then the flue gas with higher concentrations of CO2 may be         employed as a feedstock for the production of sodium bicarbonate         or sodium carbonate.     -   Note: Convert calcium silicate from the Pidgeon process to         calcium oxide or recovery calcium oxide from the Pidgeon process     -   Note: a process for enabling full conversion of calcium         carbonate or calcium silicate or a combination thereof to         calcium oxide: CO2 production process from calcium carbonate,         where the first step is to react Calcium Carbonate with equal to         or less than stoichiometric amounts of sulfurous acid or with         low vapor pressure sulfurous acid. The calcium sulfite solid is         separated from this solution using solid-liquid separation. Then         the resulting solid calcium sulfite (which may still comprise at         least a portion calcium carbonate) is transferred to a step         where it is dissolved in excess concentrated sulfurous acid,         forming dissolve calcium bisulfate and CO2 from any unreacted         calcium carbonate. Remaining CO2 is separated from the SO2 gas         atmosphere by, for example, condensation of at least a portion         of SO2 and/or a combination of other systems and/or methods. Any         non-calcium sulfite or calcium carbonate (e.g. calcium sulfate         or silica or other mostly insoluble chemicals) may remain as a         solid and may be separated from the calcium bisulfite solution         via liquid-solid separation.     -   Note: May employ calcium, or magnesium, or alkaline earth, or a         combination thereof. Calcium or magnesium or alkaline earth may         be substituted.     -   Note: In some embodiments, gas comprising sulfur dioxide may be         compressed prior to or during absorption of sulfur dioxide in         one or more or a combination of process steps described herein.     -   Note: In some embodiments, it may be desirable to avoid the         formation of dissolved calcium bisulfite. In some embodiments,         the formation of calcium bisulfite may be prevented by employing         an organic solvent, or a non-water solvent, or both instead of         or in addition to water as a solvent to absorb sulfur dioxide         and/or react sulfur dioxide with calcium carbonate, or magnesium         carbonate, or calcium silicate, or magnesium silicate, or a         calcium-‘WA’ salt, or a magnesium-‘WA’ salt, or a combination         thereof. The absence of water, or a lower concentration of         water, or the presence of other solvents than water, or a         combination thereof may inhibit the formation of dissolved         calcium bisulfite in, for example, some embodiments where it is         desired.     -   Note: ‘WA’ may comprise a weak acid. For example, ‘WA’ may         comprise an acid with acidity less than or equal to sulfurous         acid.     -   Note: A calcium silicate, or magnesium silicate, or both may         comprise at least a portion calcium carbonate in some         embodiments.     -   Note: One or more or a combination of reagents, or process         steps, or a combination thereof may be heated, or cooled, or a         combination thereof.     -   Note: Calcium silicate may comprise a material comprising         silicate. A material comprising an impure limestone comprising         at a portion a silicate material. For example, a material         comprising silicate may comprise clay, or silicon dioxide, or         alumino-silicate, or ferrite, or a combination thereof.     -   Note: Calcining of calcium sulfite may be conducted in the         presence of clay, or silicon dioxide, or shale, or sand, or iron         ore, or bauxite, or fly ash, and or slag or other materials         employed to, for example, produce or facilitate the production         of cement, or cement clinker, or a combination thereof.     -   Note: In some embodiments, it may be desirable to operate the         calcination of calcium sulfite and/or cement manufacturing         inputs in the presence of diatomic oxygen. For example, in some         embodiments, diatomic oxygen present in a flue gas stream, or in         hot gases entering or within a kiln, or a combination thereof         may react or oxidize sulfur dioxide, or calcium sulfite, or         derivatives thereof to form materials or chemicals which may be         facilitate the manufacturing of cement or clinker or may enable         advantageous properties in the cement or clinker. For example,         in some embodiments, diatomic oxygen present in a flue gas         stream, or in hot gases entering or within a kiln, or a         combination thereof may react or oxidize sulfur dioxide, or         calcium sulfite, or derivatives thereof to form calcium sulfate         and/or derivatives thereof, which may be an advantageous         ingredient or component of some cement or clinker compositions.         For example, in some embodiments, diatomic oxygen present in a         flue gas stream, or in hot gases entering or within a kiln, or a         combination thereof may react or oxidize sulfur dioxide, or         calcium sulfite, or derivatives thereof to form compounds or         materials comprising sulfur with superior strength, or chemical         resistance, or longevity, or pressure, or compressive strength,         or water resistance, or temperature resilience, or other         resilience, or cost, or adhesive properties, or chemical         compatibility, or a combination thereof. For example, in some         embodiments, diatomic oxygen present in a flue gas stream, or in         hot gases entering or within a kiln, or a combination thereof         may react with or oxidize sulfur dioxide, or calcium sulfite, or         derivatives thereof to form compounds or materials with superior         strength, or chemical resistance, or longevity, or pressure, or         compressive strength, or water resistance, or temperature         resilience, or other resilience, or cost, or adhesive         properties, or chemical compatibility, or a combination thereof.         For example, in some embodiments, diatomic oxygen present in a         flue gas stream, or in hot gases entering or within a kiln, or a         combination thereof may react with or oxidize sulfur dioxide, or         calcium sulfite, or derivatives thereof to produce heat, which         may reduce energy requirements or increase the energy efficiency         of calcining.     -   Note: In some embodiments, the use of calcium sulfite as an         input material for the production of cement may enable cement         with superior properties, which may include, but are not limited         to, superior strength, or chemical resistance, or longevity, or         pressure, or compressive strength, or water resistance, or         temperature resilience, or other resilience, or cost, or         adhesive properties, or chemical compatibility, or a combination         thereof.     -   Note: In some embodiments, calcium silicate may comprise cement         manufacturing inputs. In some embodiments, cement manufacturing         inputs may comprise calcium silicate. In some embodiments,         cement manufacturing inputs may comprise calcium sulfite, or         calcium oxide, or a combination thereof. In some embodiments,         cement manufacturing inputs may comprise calcium bisulfite.     -   Note: Weak acids and weak acid anions may include, but are not         limited to, one or more or a combination of the following:         silicates, or carbonates, or aluminates, or aluminoferrites, or         aluminum oxides, or zinc oxides, or iron oxides, or Al₂O₆, or         Al₂Fe₂O₁₀.     -   Note: In some embodiments, at least a portion of the gases         produced during or from the calcination of calcium sulfite may         comprise water or water vapor. For example, if hydrogen, or         natural gas, or ammonia, or a hydrocarbon, or other combustion,         or steam, or a combination thereof is/are employed to provide         heat for calcination, water vapor may be generated. In some         embodiments, at least a portion of said gases produced during or         from the calcination of calcium sulfite may be condensed to form         an aqueous solution comprising aqueous sulfur dioxide or         sulfurous acid. In some embodiments, said aqueous solution         comprising aqueous sulfur dioxide or sulfurous acid may be         employed as an aqueous sulfur dioxide solution or sulfurous acid         solution in one or more process steps. In some embodiments, said         aqueous solution comprising aqueous sulfur dioxide or sulfurous         acid may undergo further concentrating, or diluting, or         treating, or a combination thereof before being employed as an         aqueous sulfur dioxide solution or sulfurous acid solution in         one or more process steps.     -   Note: In some embodiments, nitrogen gas may be added to air         before combustion with said air to reduce the concentration of         oxygen before said air may be employed in the combustion of fuel         for calcining calcium sulfite. For example, a nitrogen         concentrating process may be employed. For example, an oxygen         concentrating or oxygen removal process may be employed.     -   Note: In some embodiments, at least a portion of oxygen may be         removed from air before combustion with said air to reduce the         concentration of oxygen before said air may be employed in the         combustion of fuel for calcining calcium sulfite. For example, a         nitrogen concentrating process may be employed. For example, an         oxygen concentrating or oxygen removal process may be employed.     -   Note: In some embodiments, a portion of gases after combustion         and after sulfur dioxide removal may be added to air to reduce         the concentration of diatomic oxygen before said air may be         employed in the combustion of fuel for calcining calcium         sulfite.     -   Note: In some embodiments, sulfur dioxide or carbon dioxide or         both may be added to air to reduce the concentration of diatomic         oxygen before said air may be employed in the combustion of fuel         for calcining calcium sulfite.     -   Note: It may be desirable to calcine the calcium sulfite under         conditions where the temperature is sufficiently low to prevent         produced CaO crystallites from fusing. It may be desirable to         calcine calcium sulfite under conditions and temperatures where         the specific surface of the calcium oxide remains intact. It may         be desirable to produce CaO with non-fused crystals, or where         the specific surface of the calcium oxide remains intact, or a         combination thereof for applications, which may include, but are         not limited to, the steel industry.     -   Note: It may be desirable to calcine the calcium sulfite under         conditions where the temperature is sufficiently high to         facilitate the production of fused CaO crystallites. It may be         desirable to calcine calcium sulfite under conditions and         temperatures which reduce the specific surface of the calcium         oxide. It may be desirable to produce CaO with fused crystals,         or where the specific surface of the calcium oxide is reduced,         or a combination thereof for applications, which may include,         but are not limited to, the production of aerated concrete, or         sand lime bricks, or a combination thereof.     -   Note: Heat sources may include, but are not limited to, one or         more or a combination of the following: combustion of a fuel,         hydrogen, ammonia, natural gas, heavy fuel oil, pulverised coal,         liquefied gas, off-gas from steel-making process, wood dust,         waste oil, biomass, biofuel, electricity, heat pump, solar         thermal, chemical reaction, sulfur, sulfurous fuel, sulfuric         acid production, salt production, waste heat, waste gases,         nuclear heat, geothermal, quicklime, hydration reaction,         oxidation.     -   Note: One or more of the present embodiments may produce         strongly carbon dioxide negative or negative emissions calcium         oxide     -   Note: In some embodiments, produced calcium oxide may be reacted         with carbon dioxide originating from the air or separated from         the air. For example, calcium oxide may be reacted with sodium         carbonate or potassium carbonate or sodium carbonate or         potassium carbonate solution to produce sodium hydroxide or         potassium hydroxide solution and calcium carbonate, which may be         a permanent sequestration byproduct. Said sodium hydroxide or         potassium hydroxide solution may then be contacted with air or         CO₂ originating from air to produce a solution comprising sodium         carbonate, or potassium carbonate, or a combination thereof.     -   Note: A portion of the calcium oxide produced may be converted         to calcium carbonate by reaction, with, for example, carbon         dioxide in the air, or carbon dioxide originating from the air,         or an air capture process, or regenerating an alkali-carbonate         to an alkali-oxide in an absorption loop, or regenerating an         alkali-carbonate to an alkali-oxide in an absorption or         separation process, or a combination thereof.     -   Note: A portion of the cement produced may be employed in the         production of non-hydraulic cement, or cement employing at least         a portion of CO₂ input, or a combination thereof to increase the         net CO₂ removal or emissions reduction.     -   Note: Magnesium and calcium may be present in the same input         material. For example, slags, or waste concrete, or minerals may         comprise at least a portion of magnesium. For example, dolomite         may comprise a portion of magnesium. In some embodiments, at         least a portion of magnesium sulfite and/or magnesium oxide         and/or magnesium hydroxide may be produced separately from         calcium sulfite and/or calcium oxide and/or calcium hydroxide.         For example, the separation of calcium and magnesium may be         conducted by including, but not limited to, the significant         difference in solubility in water between magnesium sulfite and         calcium sulfite and/or the significant temperature dependent         solubility of magnesium sulfite.     -   Note: The concentration of sulfur dioxide in aqueous sulfur         dioxide may be greater than or equal to one or more of the         following weight percent concentrations: 0.0001%, or 0.5%, or         1%, or 1.5%, or 2%, or 2.5%, or 3%, or 3.5%, or 4%, or 4.5%, or         5%, or 5.5%, or 6%, or 6.5%, or 7%, or 7.5%, or 8%, or 8.5%, or         9%, or 9.5%, or 10%, or 10.5%, or 11%, or 11.5%, or 12%, or         12.5%, or 13%, or 13.5%, or 14%, or 14.5%, or 15%, or 15.5%, or         16%, or 16.5%, or 17%, or 17.5%, or 18%, or 18.5%, or 19%, or         19.5%, or 20%, or 20.5%, or 21%, or 21.5%, or 22%, or 22.5%, or         23%, or 23.5%, or 24%, or 24.5%, or 25%, or 25.5%, or 26%, or         26.5%, or 27%, or 27.5%, or 28%, or 28.5%, or 29%, or 29.5%, or         30%, or 30.5%, or 31%, or 31.5%, or 32%, or 32.5%, or 33%, or         33.5%, or 34%, or 34.5%, or 35%, or 35.5%, or 36%, or 36.5%, or         37%, or 37.5%, or 38%, or 38.5%, or 39%, or 39.5%, or 40%, or         40.5%, or 41%, or 41.5%, or 42%, or 42.5%, or 43%, or 43.5%, or         44%, or 44.5%, or 45%, or 45.5%, or 46%, or 46.5%, or 47%, or         47.5%, or 48%, or 48.5%, or 49%, or 49.5%, or 50%, or 50.5%, or         51%, or 51.5%, or 52%, or 52.5%, or 53%, or 53.5%, or 54%, or         54.5%, or 55%, or 55.5%, or 56%, or 56.5%, or 57%, or 57.5%, or         58%, or 58.5%, or 59%, or 59.5%, or 60%, or 60.5%, or 61%, or         61.5%, or 62%, or 62.5%, or 63%, or 63.5%, or 64%, or 64.5%, or         65%, or 65.5%, or 66%, or 66.5%, or 67%, or 67.5%, or 68%, or         68.5%, or 69%, or 69.5%, or 70%, or 70.5%, or 71%, or 71.5%, or         72%, or 72.5%, or 73%, or 73.5%, or 74%, or 74.5%, or 75%, or         75.5%, or 76%, or 76.5%, or 77%, or 77.5%, or 78%, or 78.5%, or         79%, or 79.5%, or 80%, or 80.5%, or 81%, or 81.5%, or 82%, or         82.5%, or 83%, or 83.5%, or 84%, or 84.5%, or 85%, or 85.5%, or         86%, or 86.5%, or 87%, or 87.5%, or 88%, or 88.5%, or 89%, or         89.5%, or 90%, or 90.5%, or 91%, or 91.5%, or 92%, or 92.5%, or         93%, or 93.5%, or 94%, or 94.5%, or 95%, or 95.5%, or 96%, or         96.5%, or 97%, or 97.5%, or 98%, or 98.5%, or 99%, or 99.5%, or         99.999%     -   Note: The concentration of sulfur dioxide gas in a gas         comprising sulfur dioxide may be greater than or equal to one or         more of the following volume percent concentrations: 0.0001%, or         0.5%, or 1%, or 1.5%, or 2%, or 2.5%, or 3%, or 3.5%, or 4%, or         4.5%, or 5%, or 5.5%, or 6%, or 6.5%, or 7%, or 7.5%, or 8%, or         8.5%, or 9%, or 9.5%, or 10%, or 10.50%, or 11%, or 11.50%, or         12%, or 12.5%, or 13%, or 13.5%, or 14%, or 14.5%, or 15%, or         15.5%, or 16%, or 16.5%, or 17%, or 17.5%, or 18%, or 18.5%, or         19%, or 19.5%, or 20%, or 20.5%, or 21%, or 21.5%, or 22%, or         22.5%, or 23%, or 23.5%, or 24%, or 24.5%, or 25%, or 25.5%, or         26%, or 26.5%, or 27%, or 27.5%, or 28%, or 28.5%, or 29%, or         29.5%, or 30%, or 30.5%, or 31%, or 31.5%, or 32%, or 32.5%, or         33%, or 33.5%, or 34%, or 34.5%, or 35%, or 35.5%, or 36%, or         36.5%, or 37%, or 37.5%, or 38%, or 38.5%, or 39%, or 39.5%, or         40%, or 40.5%, or 41%, or 41.5%, or 42%, or 42.5%, or 43%, or         43.5%, or 44%, or 44.5%, or 45%, or 45.5%, or 46%, or 46.5%, or         47%, or 47.5%, or 48%, or 48.5%, or 49%, or 49.5%, or 50%, or         50.5%, or 51%, or 51.5%, or 52%, or 52.5%, or 53%, or 53.5%, or         54%, or 54.5%, or 55%, or 55.5%, or 56%, or 56.5%, or 57%, or         57.5%, or 58%, or 58.5%, or 59%, or 59.5%, or 60%, or 60.5%, or         61%, or 61.5%, or 62%, or 62.5%, or 63%, or 63.5%, or 64%, or         64.5%, or 65%, or 65.5%, or 66%, or 66.5%, or 67%, or 67.5%, or         68%, or 68.5%, or 69%, or 69.5%, or 70%, or 70.5%, or 71%, or         71.5%, or 72%, or 72.5%, or 73%, or 73.5%, or 74%, or 74.5%, or         75%, or 75.5%, or 76%, or 76.5%, or 77%, or 77.5%, or 78%, or         78.5%, or 79%, or 79.5%, or 80%, or 80.5%, or 81%, or 81.5%, or         82%, or 82.5%, or 83%, or 83.5%, or 84%, or 84.5%, or 85%, or         85.5%, or 86%, or 86.5%, or 87%, or 87.5%, or 88%, or 88.5%, or         89%, or 89.5%, or 90%, or 90.5%, or 91%, or 91.5%, or 92%, or         92.5%, or 93%, or 93.5%, or 94%, or 94.5%, or 95%, or 95.5%, or         96%, or 96.5%, or 97%, or 97.5%, or 98%, or 98.5%, or 99%, or         99.5%, or 99.999%     -   Note: The concentration of magnesium oxide in the output         comprising magnesium oxide may be greater than or equal to one         or more of the following weight percent concentrations: 0.0001%,         or 0.5%, or 1%, or 1.5%, or 2%, or 2.5%, or 3%, or 3.5%, or 4%,         or 4.5%, or 5%, or 5.5%, or 6%, or 6.5%, or 7%, or 7.5%, or 8%,         or 8.5%, or 9%, or 9.5%, or 10%, or 10.5%, or 11%, or 11.5%, or         12%, or 12.5%, or 13%, or 13.5%, or 14%, or 14.5%, or 15%, or         15.5%, or 16%, or 16.5%, or 17%, or 17.5%, or 18%, or 18.5%, or         19%, or 19.5%, or 20%, or 20.5%, or 21%, or 21.5%, or 22%, or         22.5%, or 23%, or 23.5%, or 24%, or 24.5%, or 25%, or 25.5%, or         26%, or 26.5%, or 27%, or 27.5%, or 28%, or 28.5%, or 29%, or         29.5%, or 30%, or 30.5%, or 31%, or 31.5%, or 32%, or 32.5%, or         33%, or 33.5%, or 34%, or 34.5%, or 35%, or 35.5%, or 36%, or         36.5%, or 37%, or 37.5%, or 38%, or 38.5%, or 39%, or 39.5%, or         40%, or 40.5%, or 41%, or 41.5%, or 42%, or 42.5%, or 43%, or         43.5%, or 44%, or 44.5%, or 45%, or 45.5%, or 46%, or 46.5%, or         47%, or 47.5%, or 48%, or 48.5%, or 49%, or 49.5%, or 50%, or         50.5%, or 51%, or 51.5%, or 52%, or 52.5%, or 53%, or 53.5%, or         54%, or 54.5%, or 55%, or 55.5%, or 56%, or 56.5%, or 57%, or         57.5%, or 58%, or 58.5%, or 59%, or 59.5%, or 60%, or 60.5%, or         61%, or 61.5%, or 62%, or 62.5%, or 63%, or 63.5%, or 64%, or         64.5%, or 65%, or 65.5%, or 66%, or 66.5%, or 67%, or 67.5%, or         68%, or 68.5%, or 69%, or 69.5%, or 70%, or 70.5%, or 71%, or         71.5%, or 72%, or 72.5%, or 73%, or 73.5%, or 74%, or 74.5%, or         75%, or 75.5%, or 76%, or 76.5%, or 77%, or 77.5%, or 78%, or         78.5%, or 79%, or 79.5%, or 80%, or 80.5%, or 81%, or 81.5%, or         82%, or 82.5%, or 83%, or 83.5%, or 84%, or 84.5%, or 85%, or         85.5%, or 86%, or 86.5%, or 87%, or 87.5%, or 88%, or 88.5%, or         89%, or 89.5%, or 90%, or 90.5%, or 91%, or 91.5%, or 92%, or         92.5%, or 93%, or 93.5%, or 94%, or 94.5%, or 95%, or 95.5%, or         96%, or 96.5%, or 97%, or 97.5%, or 98%, or 98.5%, or 99%, or         99.5%, or 99.999%     -   Note: The concentration of calcium oxide in the output         comprising magnesium oxide may be greater than or equal to one         or more of the following weight percent concentrations: 0.0001%,         or 0.5%, or 1%, or 1.5%, or 2%, or 2.5%, or 3%, or 3.5%, or 4%,         or 4.5%, or 5%, or 5.5%, or 6%, or 6.5%, or 7%, or 7.5%, or 8%,         or 8.5%, or 9%, or 9.5%, or 10%, or 10.50%, or 11%, or 11.50%,         or 12%, or 12.5%, or 13%, or 13.5%, or 14%, or 14.5%, or 15%, or         15.5%, or 16%, or 16.5%, or 17%, or 17.5%, or 18%, or 18.5%, or         19%, or 19.5%, or 20%, or 20.5%, or 21%, or 21.5%, or 22%, or         22.5%, or 23%, or 23.5%, or 24%, or 24.5%, or 25%, or 25.5%, or         26%, or 26.5%, or 27%, or 27.5%, or 28%, or 28.5%, or 29%, or         29.5%, or 30%, or 30.5%, or 31%, or 31.5%, or 32%, or 32.5%, or         33%, or 33.5%, or 34%, or 34.5%, or 35%, or 35.5%, or 36%, or         36.5%, or 37%, or 37.5%, or 38%, or 38.5%, or 39%, or 39.5%, or         40%, or 40.5%, or 41%, or 41.5%, or 42%, or 42.5%, or 43%, or         43.5%, or 44%, or 44.5%, or 45%, or 45.5%, or 46%, or 46.5%, or         47%, or 47.5%, or 48%, or 48.5%, or 49%, or 49.5%, or 50%, or         50.5%, or 51%, or 51.5%, or 52%, or 52.5%, or 53%, or 53.5%, or         54%, or 54.5%, or 55%, or 55.5%, or 56%, or 56.5%, or 57%, or         57.5%, or 58%, or 58.5%, or 59%, or 59.5%, or 60%, or 60.5%, or         61%, or 61.5%, or 62%, or 62.5%, or 63%, or 63.5%, or 64%, or         64.5%, or 65%, or 65.5%, or 66%, or 66.5%, or 67%, or 67.5%, or         68%, or 68.5%, or 69%, or 69.5%, or 70%, or 70.5%, or 71%, or         71.5%, or 72%, or 72.5%, or 73%, or 73.5%, or 74%, or 74.5%, or         75%, or 75.5%, or 76%, or 76.5%, or 77%, or 77.5%, or 78%, or         78.5%, or 79%, or 79.5%, or 80%, or 80.5%, or 81%, or 81.5%, or         82%, or 82.5%, or 83%, or 83.5%, or 84%, or 84.5%, or 85%, or         85.5%, or 86%, or 86.5%, or 87%, or 87.5%, or 88%, or 88.5%, or         89%, or 89.5%, or 90%, or 90.5%, or 91%, or 91.5%, or 92%, or         92.5%, or 93%, or 93.5%, or 94%, or 94.5%, or 95%, or 95.5%, or         96%, or 96.5%, or 97%, or 97.5%, or 98%, or 98.5%, or 99%, or         99.5%, or 99.999%         Additional Notes     -   Note: ‘H₂SO₃(aq)’ or ‘2SO₂(aq)+H₂O(l)’ may be employed         interchangeably.     -   Note: The weight percent concentration of SO₂ in one or more         aqueous sulfurous acid solutions or one or more solutions         comprising sulfur dioxide may be greater than or equal to one or         more or a combination of the following: 0.001%, or 0.1%, or 1%,         or 2%, or 3%, or 4%, or 5%, or 6%, or 7%, or 8%, or 9%, or 10%,         or 11%, or 12%, or 13%, or 14%, or 15%, or 16%, or 17%, or 18%,         or 19%, or 20%, or 21%, or 22%, or 23%, or 24%, or 25%, or 26%,         or 27%, or 28%, or 29%, or 30%, or 31%, or 32%, or 33%, or 34%,         or 35%, or 36%, or 37%, or 38%, or 39%, or 40%, or 41%, or 42%,         or 43%, or 44%, or 45%, or 46%, or 47%, or 48%, or 49%, or 50%,         or 51%, or 52%, or 53%, or 54%, or 55%, or 56%, or 57%, or 58%,         or 59%, or 60%, or 61%, or 62%, or 63%, or 64%, or 65%, or 66%,         or 67%, or 68%, or 69%, or 70%, or 71%, or 72%, or 73%, or 74%,         or 75%, or 76%, or 77%, or 78%, or 79%, or 80%, or 81%, or 82%,         or 83%, or 84%, or 85%, or 86%, or 87%, or 88%, or 89%, or 90%,         or 90.5%, or 91%, or 91.5%, or 92%, or 92.5%, or 93%, or 93.5%,         or 94%, or 94.5%, or 95%, or 95.5%, or 96%, or 96.5%, or 97%, or         97.5%, or 98%, or 98.5%, or 99%, or 99.5%, or 99.9%, or less         than or equal to 100%.     -   Note: The volume percent concentration of SO₂ in one or more         gases described herein may be greater than or equal to one or         more or a combination of the following: 0.001%, or 0.1%, or 1%,         or 2%, or 3%, or 4%, or 5%, or 6%, or 7%, or 8%, or 9%, or 10%,         or 11%, or 12%, or 13%, or 14%, or 15%, or 16%, or 17%, or 18%,         or 19%, or 20%, or 21%, or 22%, or 23%, or 24%, or 25%, or 26%,         or 27%, or 28%, or 29%, or 30%, or 31%, or 32%, or 33%, or 34%,         or 35%, or 36%, or 37%, or 38%, or 39%, or 40%, or 41%, or 42%,         or 43%, or 44%, or 45%, or 46%, or 47%, or 48%, or 49%, or 50%,         or 51%, or 52%, or 53%, or 54%, or 55%, or 56%, or 57%, or 58%,         or 59%, or 60%, or 61%, or 62%, or 63%, or 64%, or 65%, or 66%,         or 67%, or 68%, or 69%, or 70%, or 71%, or 72%, or 73%, or 74%,         or 75%, or 76%, or 77%, or 78%, or 79%, or 80%, or 81%, or 82%,         or 83%, or 84%, or 85%, or 86%, or 87%, or 88%, or 89%, or 90%,         or 90.5%, or 91%, or 91.5%, or 92%, or 92.5%, or 93%, or 93.5%,         or 94%, or 94.5%, or 95%, or 95.5%, or 96%, or 96.5%, or 97%, or         97.5%, or 98%, or 98.5%, or 99%, or 99.5%, or 99.9%, or less         than or equal to 100%.     -   Note: ‘WA’ may comprise a weak acid, which may include, but not         limited to, silicic acid, or orthosilicic acid, or silicon acid         derivatives, or silicon minerals, or silicon acids, or         aluminates, or ferrates, or a combination thereof.     -   Note: Some embodiments may involve reacting calcium silicate or         a material comprising silicon directly with sulfur dioxide or         sulfur dioxide in an non-aqueous solution or a combination         thereof.     -   Note: In some embodiments, contaminants or impurities may         dissolve in a solution comprising sulfur dioxide, or due to the         presence of sulfuric acid, or a combination thereof.         Contaminants or impurities may include, but are not limited to,         one or more or a combination of the following: iron, or         aluminum, or alkali metals, or transition metals, or other         non-bisulfite soluble salts, or non-alkaline earth bisulfite         salts, or a combination thereof. In some embodiments, dissolved         contaminants may be present after solid-liquid separation,         and/or after calcium sulfite precipitation. In some embodiments,         at least a portion of contaminants may be separated periodically         or continuously. Contaminants may be separated by, including,         but not limited to, precipitation, or membrane based process, or         cooling, or heating, or crystallization, or cryodesalination, or         a separation process described herein, or a separation process         in the art, or a combination thereof.     -   Note: ‘Calcium’ may also refer to magnesium and/or other         alkaline earth metals.     -   Note: In some embodiments, one absorption column, or absorption         step, or absorption process, or a combination thereof may be         employed to absorb sulfur dioxide gas and form aqueous sulfur         dioxide or a sulfurous acid solution. In some embodiments, more         than one absorption column, or absorption step, or absorption         process, or a combination thereof may be employed to absorb         sulfur dioxide gas and form aqueous sulfur dioxide or a         sulfurous acid solution.     -   Note: Calcining kilns may include, but are not limited to, one         or more or a combination of the following: Shaft kilns, or         Counter-current shaft kilns, or Regenerative kilns, or Annular         kilns, or Rotary kilns.         Additional Notes     -   Note: ‘WA’ may comprise a weak acid, which may include, but not         limited to, silicic acid, or orthosilicic acid, or silicon acid         derivatives, or silicon minerals, or silicon acids, or         aluminates, or ferrates, or a combination thereof.     -   Note: Calcium or magnesium-weak acid input may comprise, for         example, including, but not limited to, one or more or a         combination of the following: carbonates, or bicarbonates, or         silicates, or silicate derivatives, or minerals, or concrete, or         cement, or waste concrete, or waste cement, or steel slag, or         fly ash, or ash, or limestone, or rock.     -   Note: In some embodiments, higher partial pressure CO₂, or         higher concentration CO₂, or pure CO₂(g), or high partial         pressure CO₂(g), or CO₂(l), or CO₂(g), may be employed to         facilitate formation of bicarbonate salts. For example, in some         embodiments, one or more or a combination of the following may         be employed:         -   At least a portion of CO₂ input may be sourced from a             reaction of calcium carbonate with sulfurous acid         -   At least a portion of CO₂ input may be sources from CO₂             sources produced within the process, or other CO₂ sources,             or a combination thereof         -   At least a portion of CO₂ input may be sourced from CO₂             captured from a combustion source, or a combustion source             employed to produce heat, or emissions source, or air, or             geological CO₂ source, or natural CO₂ source, or a             combination thereof.     -   Note: CO₂ sources include, but are not limited to,     -   Note: Some embodiments may be designed to operate as a low         temperature process, where the solutions and/or solid reagents         in thermal desorption or decomposition may undergo or operate         thermal desorption or decomposition at less than 150° C., or         less than 200° C., or less than 250° C., or less than 300° C.,         or less than 350° C.     -   Note: In some embodiments, at least a portion of heat may be         supplied by a heat pump, or a refrigeration cycle, or a         combination thereof. A heat pump may comprise, including, but         not limited to, a mechanical, or thermal, or absorption, or a         combination thereof process. A heat pump may be powered by,         including, but not limited to, electricity, or heat, or photons,         or chemical reaction, or radiation, or mechanical work, or         pneumatic process, or hydraulic process, or expansion, or         compression, or evaporation, or absorption, or vapor pressure         differences, or osmotic pressure differences, or temperature         differences, or pressure differences, or a combination thereof.     -   Note: In some embodiments, sulfides and/or hydrogen sulfide may         comprise a weak acid or weak acid anion.     -   Note: Separations for removing accumulating water, or removing         water, or recovering water, or concentrating, or crystalizing,         or precipitating, or separating, or removing, or a combination         thereof may include, but are not limited to, one or more or a         combination of the following: falling film evaporator,         mechanical vapor compression (MVC), or mechanical vapor         recompression, or multi-effect distillation (MED), or         multi-stage flash distillation (MSF), or vapor compression (VC)         distillation, or vacuum vapor compression (VVC), or membrane         distillation, or evaporation, or distillation, or forward         osmosis, or reverse osmosis, or nanofiltration, or hot         nanofiltration, or hot reverse osmosis, or hot concentrating         followed by cooling precipitation, or hot concentrating followed         by cooling precipitation and solid-liquid separation, or heating         precipitation, centrifuge, settling, or filter, or rotary         filter, or calcining, or desorption, or absorption, or         coalescing, or decanting, or aggregation, or coagulation, or         frothing, or density based methods, or surface tension based         methods, or foaming separation, emulsification, or         de-emulsification, or flocculation, solventing out, or salting         out, or cooling precipitation, or heating, or cryodesalination,         or zero liquid discharge processes, or crystallization         processes, or electrodialysis reversal (EDR), or electrodialysis         process, or magnetic separation, or eddy currents, or         electromagnetic induction, or filtration, or activated carbon,         or ion exchange, or ion exchange membrane, or precipitation         process, or cryodesalination, or cooling desalination, or         cooling, or heating, or salting-out, or solventing-out, or         adding a solvent to precipitate a solid and then removing the         added solvent, or a combination thereof.     -   Note: Some embodiments may employ an inert gas, such as nitrogen         or argon, or a gas other than diatomic oxygen, such as CO₂, or a         combination thereof in the headspace to prevent, for example,         oxidation of or reaction of oxygen with sulfite, metabisulfite,         bisulfite, sulfur dioxide, sulfurous acid, or a combination         thereof.     -   Note: Magnesium or other alkaline earth or alkaline earth salts         may be employed instead of or in addition to calcium.     -   Note: Concrete waste may be produced in excess of 600 million         tons annually in the USA alone, which is more than twice the         amount of generated municipal solid waste.     -   Note: At least a portion of sulfur dioxide may be lost in one or         more or a combination of steps. Alternatively, or additionally,         sulfur dioxide may be exit the process as a, for example, a         residual, in one or more outputs. Sulfur dioxide or ‘make-up         sulfur dioxide’ may be added to the process. In some         embodiments, sulfur dioxide may be stored on site and added as         desired or needed to the process. In some embodiments, elemental         sulfur, or hydrogen sulfide, or a salt comprising sulfur, or         sulfide salt, or sulfite salt, or sulfate salt, or a combination         thereof may be a source of sulfur dioxide or sulfurous acid, by,         for example, including, but not limited to, one or more or a         combination thereof: combustion, or acid-base reaction, or         reaction with an acid, or carbothermic reduction, or thermal or         decomposition, or electrolysis, or electrodialysis, or         electrochemical reaction.     -   Note: In some embodiments, at least a portion of calcium sulfate         may be removed. For example, a portion of residual dissolved         calcium sulfate may precipitate and may be removed by, for         example, including, but not limited to, solid-liquid separation,         or removal of calcium sulfate scaling, or a combination thereof.     -   Note: One or more or a combination of steps in one or more         embodiments may require heating and/or cooling. For example, a         reaction of sulfurous acid with a calcium-weak acid or         magnesium-weak acid may require or may be facilitated by cooling         or heating. Alternatively, or additionally, heat or heating or         cooling or a combination thereof may be recovered from one or         more or a combination of reaction steps. In some embodiments,         heat or heating or cooling or a combination thereof may be         recovered and said recovered heat or heating or cooling or a         combination thereof may be transferred or employed in one or         more other steps, or in the same step, or in other applications.     -   Note: Losses may occur during the process. Makeup streams of one         or more or a combination of reagents may be added.     -   Note: Contaminants may exist or accumulate in the process. If         desired, one or more contaminants may be at least partially         removed periodically, or continuously, or as desired, or a         combination thereof.     -   Note: Other acid gases may be employed instead of or in addition         to sulfur dioxide, which may include, but are not limited to,         nitrogen oxides, or nitrogen dioxide, or nitrogen monoxide, or         dinitrogen tetroxide, or nitric acid, or carbon dioxide, or         carbonic acid, or hydrogen sulfuric, or sulfonic acid, or         hydrosulfuric acid, or organo-sulfurous compounds, or         hydrochloric acid, or hydrobromic acid, or hydroiodic acid, or         hydrogen cyanide, or sulfuric acid, or perchloric acid, or         nitrous acid, or hydrofluoric acid, or nitrogen derivative         acids, or halogen derivative acids, or derivatives thereof, or a         combination thereof.     -   Note: At least a portion of heat may be provided from the         reaction of calcium oxide with water to form calcium hydroxide         or a calcium hydroxide solution.     -   Note: Calcium-weak acid or magnesium-weak acid salts or ‘WA’ may         include, but are not limited, salts of organic acids. Organic         acids, or carboxylic acids, or organic acid anions, or a         combination thereof may include, but are not limited to, one or         more or a combination of the following: citric acid, or         aconitates, or citrates, or isocitrates, or alloisocitrate, or         oxalic acid, or acetic acid, or carboxylic acids, or lactic         acid, or aconitic acid, or formic acid, or uric acid, or malic         acid, or tartaric acid, methanoic acid, or hydroxymethanoic         acid, or ethanoic acid, or 2-hydroxyethanoic acid, or         oxoethanoic acid, or ethanedioic acid, or propanoic acid, or         propenoic acid, or propynoic acid, or 2-hydroxypropanoic acid,         or 3-hydroxypropanoic acid, or 2,3-dihydroxypropanoic acid, or         2-oxopropanoic acid, or 3-oxopropanoic acid, or         2,3-dioxopropanoic acid, or propanedioic acid, or         2-hydroxypropanedioic acid, or 2,2-dihydroxypropanedioic acid,         or oxopropanedioic acid, or oxirane-2-carboxylic acid, or         butanoic acid, or 2-methylpropanoic acid, or (E)-but-2-enoic         acid, or (Z)-but-2-enoic acid, or 2-methylpropenoic acid, or         but-3-enoic acid, or but-2-ynoic acid, or 2-hydroxybutanoic         acid, or 3-hydroxybutanoic acid, or 4-hydroxybutanoic acid, or         2-oxobutanoic acid, or 3-oxobutanoic acid, or 4-oxobutanoic         acid, or butanedioic acid, or 2-methylpropanedioic acid, or         (E)-butenedioic acid, or (Z)-butenedioic acid, or butynedioic         acid, or hydroxybutanedioic acid, or 2,3-dihydroxybutanedioic         acid, or oxobutanedioic acid, or dioxobutanedioic acid, or         pentanoic acid, or 3-methylbutanoic acid, or 2-methylbutanoic         acid, or 2,2-dimethylpropanoic acid, or 3-hydroxypentanoic acid,         or 4-hydroxypentanoic acid, or 3-hydroxy-3-methylbutanoic acid,         or pentanedioic acid, or 2-oxopentanedioic acid, or         3-oxopentanedioic acid, or furan-2-carboxylic acid, or         tetrahydrofuran-2-carboxylic acid, or hexanoic acid, or         hexanedioic acid, or 2,3-dimethylbutanoic acid, or         3,3-dimethylbutanoic acid, or         2-hydroxypropane-1,2,3-tricarboxylic acid, or         prop-1-ene-1,2,3-tricarboxylic acid, or         1-hydroxypropane-1,2,3-tricarboxylic acid, or         (2E,4E)-hexa-2,4-dienoic acid, or heptanoic acid, or         heptanedioic acid, or cyclohexanecarboxylic acid, or         benzenecarboxylic acid, or 2-hydroxybenzoic acid, or         4-carboxybenzoic acid, or 2,2-dimethylpentanoic acid, or         2,3-dimethylpentanoic acid, or 2,4-dimethylpentanoic acid, or         3,3-dimethylpentanoic acid, or 2-ethylpentanoic acid, or         3-ethylpentanoic acid, or 2-methylhexanoic acid, or         3-methylhexanoic acid, or 2,2,3-trimethylbutanoic acid, or         2-ethyl-2-methylbutanoic acid, or 2-ethyl-3-, or methylbutanoic         acid, or octanoic acid, or benzene-1,2-dicarboxylic acid, or         2-methylheptanoic acid, or 3-methylheptanoic acid, or         4-methylheptanoic acid, or 5-methylheptanoic acid, or         6-methylheptanoic acid, or 2,2-dimethylhexanoic acid, or         2,3-dimethylhexanoic acid, or 2,4-dimethylhexanoic acid, or         2,5-dimethylhexanoic acid, or 3,3-dimethylhexanoic acid, or         3,4-dimethylhexanoic acid, or 3,5-dimethylhexanoic acid, or         4,4-dimethylhexanoic acid, or 4,5-dimethylhexanoic acid, or         5,5-dimethylhexanoic acid, or 2-ethanehexanoic acid, or         3-ethanehexanoic acid, or 4-ethanehexanoic acid, or         5-ethanehexanoic acid, or 2-octenoic acid, or 3-octenoic acid,         or 4-octenoic acid, or 5-octenoic acid, or 6-octenoic acid, or         7-octenoic acid, or nonanoic acid, or         benzene-1,3,5-tricarboxylic acid, or (E)-3-phenylprop-2-enoic         acid, or decanoic acid, or decanedioic acid, or undecanoic acid,         or dodecanoic acid, or benzene-1,2,3,4,5,6-hexacarboxylic acid,         or tridecanoic acid, or tetradecanoic acid, or pentadecanoic         acid, or hexadecanoic acid, or heptadecanoic acid, or         octadecanoic acid, or (9Z)-octadec-9-enoic acid, or         (9Z,12Z)-octadeca-9,12-dienoic acid, or         (9Z,12Z,15Z)-octadeca-9,12,15-trienoic acid, or         (6Z,9Z,12Z)-octadeca-6,9,12-trienoic acid, or         (6Z,9Z,12Z,15Z)-octadeca-6,9,12,15-tetraenoic acid, or         nonadecanoic acid, or eicosanoic acid, or         (5Z,8Z,11Z)-eicosa-5,8,11-trienoic acid, or         (5Z,8Z,11Z,14Z)-eicosa-5,8,11,14-tetraenoic acid, or         (5Z,8Z,11Z,14Z,17Z)-eicosa-5,8,11,14-pentaenoic acid, or         heneicosanoic acid, or docosanoic acid, or         (4Z,7Z,10Z,13Z,16Z,19Z)-docosa-4,7,10,13,16,19-hexaenoic acid,         or tricosanoic acid, or tetracosanoic acid, or pentacosanoic         acid, or hexacosanoic acid, or amino acids, or glutamate, or         glutamic acid.     -   Note: Weak acids or organic acids may include, but are not         limited to, one or more or a combination of the following:         carboxylic acids, or sulfonic acids, or alcohols, or thiols, or         enols, or phenols, or carbonic acid     -   Note: Calcium citrate may be in the form of tri-calcium citrate         tetrahydrate.     -   Note: Separated citric acid may be in the form of an aqueous         solution, or citric acid monohydrate, or anhydrous citric acid,         or a combination thereof.     -   Note: Remaining solution after removal of citric acid may be         treated with activated carbon, or passed through cation or anion         exchangers, or an anion exchange resin, or a cation exchanger         resin, or a combination thereof.     -   Note: Citric acid, or other carboxylic acid, or organic acid, or         a combination thereof may be separated from or recovered from         including, but not limited to, one or more or a combination of         the following: fermentation broth, or sugar broths, or sugars,         or raw sugars, or raw agricultural feedstocks, or agricultural         byproducts, or sugar refining liquids, or mold produced citric         acid, or juices, or fungi produced acids, or liquids or acids         produced by Aspergillus niger, or sucrose broth, or dextrose         broth, or glucose broth, or corn steep liquor, or molasses, or         hydrolyzed corn starch, or citrus fruits, or fruit juices. Said         separating or recovering may involve reaction or contacting with         calcium hydroxide or aqueous calcium hydroxide solution.     -   Note: Heat may be recovered in one or more process steps and may         employed in one or more other process steps, or within the same         process step, or both.     -   Note: Calcium citrate may be provided as an example organic acid         salt of calcium.     -   Note: Calcium may be provided as an example alkaline earth metal         or alkaline earth metal cation or alkaline earth metal cation         salt.     -   Note: Calcium silicate may be provided as an example weak acid         salt of calcium or an example reagent representing a wide array         of compositions or minerals comprising calcium, magnesium,         silicon, oxygen, and derivatives thereof.     -   Note: Calcium oxide produced may be reacted with water to         produce calcium hydroxide or a solution comprising aqueous         calcium hydroxide. The aqueous calcium hydroxide may be reacted         with CO₂, such as a gas comprising CO₂, to produce precipitate         calcium carbonate and water. For example, aqueous sodium         hydroxide may be reacted with flue gas, or raw gas, or air, or         gases produced from fuel combusted to power the calciner, or         remaining gases after absorption of sulfur dioxide, or other gas         comprising at least a portion CO₂, or a combination thereof.         Some embodiments of the present invention may be employed to         produce CO₂-emissions neutral or negative precipitated calcium         carbonate. Some embodiments of the present invention may involve         producing CO₂-emissions neutral or negative precipitated calcium         carbonate using CO₂ from the air or captured from the air using         the presently described process.     -   Note: Calcium oxide produced may be reacted with water to         produce calcium hydroxide or a solution comprising aqueous         calcium hydroxide. The aqueous calcium hydroxide may be reacted         sodium carbonate, such as an aqueous solution of sodium         carbonate, to produce precipitate calcium carbonate and aqueous         sodium hydroxide. The precipitated calcium carbonate may be         separated from the aqueous sodium hydroxide and may comprise a         valuable byproduct. The aqueous sodium hydroxide may be reacted         with a gas comprising carbon dioxide to produce aqueous sodium         carbonate. For example, aqueous sodium hydroxide may be reacted         with flue gas, or raw gas, or air, or gases produced from fuel         combusted to power the calciner, or remaining gases after         absorption of sulfur dioxide, or other gas comprising at least a         portion CO₂, or a combination thereof. Some embodiments of the         present invention may be employed to produce CO₂-emissions         neutral or negative precipitated calcium carbonate. Some         embodiments of the present invention may involve producing         CO₂-emissions neutral or negative precipitated calcium carbonate         using CO₂ from the air or captured from the air using the         presently described process. Some embodiments of the present         invention may involve producing CO₂-emissions neutral or         negative precipitated calcium carbonate using CO₂ from emissions         sources, or air, or both using the presently described process.     -   Note: The weight percent concentration of one or more or a         combination of reagents may include, but is not limited to, less         than, or equal to, or greater than one or more or a combination         of the following: 0%, or 0.5%, or 1%, or 1.5%, or 2%, or 2.5%,         or 3%, or 3.5%, or 4%, or 4.5%, or 5%, or 5.5%, or 6%, or 6.5%,         or 7%, or 7.5%, or 8%, or 8.5%, or 9%, or 9.50%, or 10%, or         10.5%, or 11%, or 11.50%, or 12%, or 12.5%, or 13%, or 13.5%, or         14%, or 14.5%, or 15%, or 15.5%, or 16%, or 16.5%, or 17%, or         17.5%, or 18%, or 18.5%, or 19%, or 19.5%, or 20%, or 20.5%, or         21%, or 21.5%, or 22%, or 22.5%, or 23%, or 23.5%, or 24%, or         24.5%, or 25%, or 25.5%, or 26%, or 26.5%, or 27%, or 27.5%, or         28%, or 28.5%, or 29%, or 29.5%, or 30%, or 30.5%, or 31%, or         31.5%, or 32%, or 32.5%, or 33%, or 33.5%, or 34%, or 34.5%, or         35%, or 35.5%, or 36%, or 36.5%, or 37%, or 37.5%, or 38%, or         38.5%, or 39%, or 39.5%, or 40%, or 40.5%, or 41%, or 41.5%, or         42%, or 42.5%, or 43%, or 43.5%, or 44%, or 44.5%, or 45%, or         45.5%, or 46%, or 46.5%, or 47%, or 47.5%, or 48%, or 48.5%, or         49%, or 49.5%, or 50%, or 50.5%, or 51%, or 51.5%, or 52%, or         52.5%, or 53%, or 53.5%, or 54%, or 54.5%, or 55%, or 55.5%, or         56%, or 56.5%, or 57%, or 57.5%, or 58%, or 58.5%, or 59%, or         59.5%, or 60%, or 60.5%, or 61%, or 61.5%, or 62%, or 62.5%, or         63%, or 63.5%, or 64%, or 64.5%, or 65%, or 65.5%, or 66%, or         66.5%, or 67%, or 67.5%, or 68%, or 68.5%, or 69%, or 69.5%, or         70%, or 70.5%, or 71%, or 71.5%, or 72%, or 72.5%, or 73%, or         73.5%, or 74%, or 74.5%, or 75%, or 75.5%, or 76%, or 76.5%, or         77%, or 77.5%, or 78%, or 78.5%, or 79%, or 79.5%, or 80%, or         80.5%, or 81%, or 81.5%, or 82%, or 82.5%, or 83%, or 83.5%, or         84%, or 84.5%, or 85%, or 85.5%, or 86%, or 86.5%, or 87%, or         87.5%, or 88%, or 88.5%, or 89%, or 89.5%, or 90%, or 90.5%, or         91%, or 91.5%, or 92%, or 92.5%, or 93%, or 93.5%, or 94%, or         94.5%, or 95%, or 95.5%, or 96%, or 96.5%, or 97%, or 97.5%, or         98%, or 98.5%, or 99%, or 99.5%, or 100%     -   Note: Calcium silicate input or magnesium silicate input may         comprise a slag. For example, global iron slag production is         estimated to be 320 million to 384 million tons annually and         steel stag is estimated to be between 190 million to 280 million         tons annually. Other slags may include, but are not limited to,         slags from magnesium production. Slags are generally produced         when calcium oxide or magnesium oxide are added to a metal         production process to remove impurities, or facilitate certain         conditions or properties, or a combination thereof. The present         invention may convert said slags into calcium oxide or magnesium         oxide or other alkaline earth oxide. The present invention may         enable a circular economy in the iron-marking, or steel-making,         or other metal production industries because calcium oxide         and/or magnesium oxide are used as the inputs which result in         the production of slag. If iron or steel makers can recycle at         least a portion of slag into calcium oxide or magnesium oxide,         iron or steel makers may greatly reduce or eliminate their need         to purchase calcium oxide or magnesium oxide, significantly         reducing operating costs. If at least a portion of iron or steel         stag is recycled into calcium oxide or magnesium oxide, iron         and/or steel production lifecycle carbon dioxide emissions will         be greatly reduced.     -   Note: Calcium sulfite and/or magnesium sulfite may comprise         hydrates. For example, magnesium sulfite may form a hexahydrate,         or a trihydrate, or may be anhydrous. For example, calcium         sulfite may form a tetrahydrate, or a hemihydrate, or may be         anhydrous. It may be desirable to dehydrate at least a portion         of the hydrate of calcium sulfite, or magnesium sulfite, or both         before or during calcining of a sulfite into an oxide and sulfur         dioxide. It may be desirable to dehydrate at least a portion of         the hydrate of calcium sulfite, or magnesium sulfite, or both         before calcining of a sulfite into an oxide and sulfur dioxide.         For example, magnesium sulfite hexahydrate may be heated to         above 40° C., where magnesium sulfite hexahydrate may decompose         or dehydrate into magnesium sulfite trihydrate. For example,         calcium sulfite tetrahydrate may be heated to decompose or         dehydrate into calcium sulfite hemihydrate. For example, calcium         and/or magnesium hydrates may be decomposed or dehydrated into         anhydrous forms. For example, calcium sulfite hydrate and/or         magnesium sulfite hydrate may be heated to decompose or         dehydrate into anhydrous forms. Dehydrating hydrates may require         heat or other energy. It may be desirable to supply said heat or         other energy for dehydrating hydrates from lower cost, or lower         quality heat sources, such as, including, but not limited to,         one or more or a combination of the following: waste heat, or         heat from other process steps, or low quality steam, or medium         quality steam, or high quality step, or combustion of one or         more fuels, or solar thermal, or slacking lime, or hydrating a         oxide to a hydroxide, or other heat source.     -   Note: Systems and methods may be employed to remove impurities,         or prevent or minimize accumulation of impurities, or a         combination thereof. For example, input materials may comprise         impurities other than desired reagents. In some instances, said         impurities or contaminants may accumulate, or may result in the         formation of other impurities, or a combination thereof. In some         instances, impurities may dissolve in one or more solutions in         the process. Impurities may be removed, or treated, or         separated, by, including, but not limited to, one or more or a         combination of the following: chemical reaction, or         electrodialysis, or ion-exchanger, or precipitation, or cooling,         or heating, or distillation, or membrane-based process, or         solventing-out, or salting out.     -   Note: At least a portion of the weak acid product, or         undissolved materials, or a combination thereof are employed as         a concrete aggregate.     -   Note: At least a portion of the weak acid product, or         undissolved materials, or a combination thereof may be disposed         of or may comprise a waste product.     -   Note: A material comprising calcium and/or magnesium may         comprise a material comprising an alkaline-earth.         Alkaline-earths may include one or more or a combination of the         following: beryllium (Be), or magnesium (Mg), or calcium (Ca),         or strontium (Sr), or barium (Ba), or radium (Ra)     -   Note: In some embodiments, a material comprising calcium and/or         magnesium may further comprise one or more or a combination of         the following: iron oxides, or iron, or manganese oxide, or         manganese, may include, but are not limited to, one or more or a         combination of the following: iron (II), or iron (II,III), or         iron (III), or iron (II) oxide, or iron (II,II) oxide, or         iron (III) oxide, or iron sulfite, or iron sulfate, or iron         sulfide, or iron, or ferrites, or ferrates, or calcium-iron         salts, or magnesium iron salts, or iron silicate salts, or iron         silicon salts, or iron carbon salts, or manganese salts, or         manganese −3, or manganese −2, or manganese −1, or manganese 0,         or manganese +1, or manganese +2, or manganese, or manganese +3,         or manganese +4, or manganese +5, or manganese +6, or manganese         +7, or manganese sulfite, or manganese oxide, or manganese         carbonate, or manganese-iron, or calcium-manganese, or         calcium-manganese salts, or magnesium-manganese, or         magnesium-manganese salts, or manganese silicon, or manganese         carbon, or manganese     -   Note: The properties of iron and manganese may be similar.         Manganese may be present in some materials which may comprise         iron, such as some slags, or concretes, or minerals. In some         embodiments, iron and manganese may be used interchangeably.     -   Note: Solutions comprising salts of metals lead, or copper, or         gold, or silver, or zinc, or aluminum, or chromium, or cobalt,         or manganese, or rare-earth metals, or iron, or molybdenum, or         cadmium, or nickel, or silver, or cobalt, or zinc, or gold, or         platinum, or platinum group metals, or a combination thereof may         undergo a separations and/or refining process. For example, one         or more or a combination of said metals may be separated or         produced from solution or from a separated state or both by         means of, for example, including, but not limited to, one or         more or a combination of the following: electrolytic refining,         or electrowinning, or electroextraction, or electrodeposition.         For example, a solution comprising aqueous iron bisulfite, or         manganese bisulfite, or iron sulfate, or manganese bisulfate, or         iron chloride, or magnesium chloride may undergo         electroextraction to produce manganese, iron, or a combination         thereof. In some embodiments, one or more or a combination of         the aforementioned metals may be separated by reaction with         hydrogen sulfide or sulfur to produce a sulfide or an insoluble         sulfide, then said sulfide may be converted into a form for use         as in input to an electroextraction process.     -   Note: Separation of at least a portion of iron sulfite solid         from at least a portion of calcium sulfite solid, or separation         of iron from calcium or magnesium, or a combination thereof may         be conducted by, including, but not limited to, one or more or a         combination of the following: density based separation, or         floatation and sinking separation using a dense liquid, or         separation using a dense liquid, or separation using a liquid         with a lower density than iron sulfite and a greater density         than calcium sulfite, or magnetic separation, or magnetic         separation of iron from calcium, or oxidation of iron, or         reaction of solution comprising dissolved iron with hydrogen         sulfide to produce iron sulfide solid precipitate, or reaction         of solution comprising calcium with sulfuric acid to form         calcium sulfate precipitate, or frothing, or floatation, or         solid separation, or centrifuge, or grinding, or pulverization,         or reaction of iron sulfite and calcium sulfite solids with         sulfuric acid to form dissolved or aqueous iron sulfate and         calcium sulfate solid, or reaction of a mixture of calcium oxide         and iron oxide with water to form calcium hydroxide dissolved or         aqueous and iron oxide solid, or precipitation of iron sulfite         before calcium sulfite, or precipitation of calcium sulfite         before iron sulfite, or electrodialysis, or electrodialysis         reversal, or ion exchange, or iron exchange resin, or iron         reaction, or double-salt reaction, or precipitation reaction, or         temperature driven precipitation, or concentration driven         precipitation     -   Note: Oxygen or ‘oxide’ or ‘hydroxide’ or a combination thereof         may be considered weak acids or ‘weak acid anions’ or a         combination thereof.     -   Note: Desorption of sulfur dioxide form a solution comprising         bisulfite may be conducted by, for example, including, but not         limited to, one or more or a combination of the following:         thermal desorption, or steam stripping, or a combination         thereof. A solution comprising bisulfite may include, but is not         limited to, a solution comprising one or more or a combination         of the following: alkaline earth bisulfite, or magnesium         bisulfite, or calcium bisulfite, or iron bisulfite, or manganese         bisulfite, or zinc bisulfite, or sulfur dioxide, or water, or         sulfurous acid.     -   Note: Separations may include, but are not limited to, one or         more or a combination of the following: Separation by density,         or Separation by magnetism, or Separation by frothing or surface         tension, or Separation by residual solubility differences, or         Separation by oxidation, or Separation by ion exchange, or         Separation by reaction with an alkali hydroxide solution, or         Separation by reaction with hydrogen sulfide, or Separation by         reaction with aqueous sulfuric acid, or Separation by density         using a high density liquid with a density less than at least         one salt and a density greater than one salt, or Separation by         density using a high density liquid with a density less than         iron sulfite and a density greater than calcium sulfite, or         Separation by density using a centrifuge, or Separation by a         magnetic field using a mixing and an externally applied magnetic         field, or Separation by reaction with and/or dissolution in         water, or Grinding or pulverization, or Separation by froth         flotation, or Other solid-solid separation method, or Other         method for separating iron from calcium, or Other separation         method     -   Note: In some embodiments, remaining solution after separating         magnesium sulfite solid using a solid-liquid separate process         may be further treated with, including, but not limited to, one         or more or a combination of the following: ion exchange, or         resins, or filters, or chemical treatments, or chemical         reactions, or membrane based process, or distillation, or         cooling, or heating, or freezing, or cryodesalination, or         solventing-out, or solvent induced precipitation, or         salting-out, or other treatment. One or more solutions         comprising water may be transferred to a sulfur dioxide         absorption step, or mixed with a solution transferred to a         sulfur dioxide absorption step, or a combination thereof.         Example Embodiments Metal Oxides Production         1. A process for producing calcium oxide, magnesium oxide, or         both from a material comprising calcium and magnesium wherein         the process comprises:

reacting a material comprising calcium carbonate and magnesium carbonate with a solution comprising aqueous sulfur dioxide to form a gas comprising CO₂, a liquid solution comprising aqueous magnesium sulfite, and a solid comprising calcium sulfite;

separating said solid comprising calcium sulfite from said liquid solution comprising aqueous magnesium sulfite;

concentrating said aqueous magnesium sulfite using a membrane based process to form a concentrate solution comprising magnesium sulfite and a permeate comprising water;

precipitating solid magnesium sulfite from said concentrate solution comprising aqueous magnesium sulfite; and

calcining said solid calcium sulfite to produce calcium oxide or cement or calcining said solid magnesium sulfite to produce magnesium oxide or cement.

2. The process of example embodiment 1 wherein said membrane based process comprises reverse osmosis, or forward osmosis, or both.

3. The process of example embodiment 1 wherein said concentrating is conducted at a temperature greater than about 35° C. and less than about 100° C.

4. The process of example embodiment 1 wherein said precipitating comprises cooling said concentrate solution to a temperature of less than about 35° C.

5. The process of example embodiment 1 which further comprises drying before calcining.

6. The process of example embodiment 5 wherein said drying is at least partially conducted at a temperature less than a temperature of calcining.

7. The process of example embodiment 5 wherein at least a portion of heat for said drying is supplied by reacting calcium oxide with water, or reacting magnesium oxide with water, or both.

8. The process of example embodiment 5 wherein a carrier gas comprising water vapor is employed during drying and wherein the process further comprising removing at least a portion of water vapor from said carrier gas.

9. The process of example embodiment 8 wherein the removing comprises reacting the water vapor with calcium oxide to form calcium hydroxide.

10. The process of example embodiment 8 wherein the removing comprises reacting the water vapor with a non-regenerated desiccant.

11. The process of example embodiment 8 wherein the removing comprises employing a liquid desiccant, or a solid desiccant, or both.

12. The process of example embodiment 8 wherein the removing comprises employing a membrane-based process.

13. The process of example embodiment 8 wherein the removing comprises condensing.

14. The process of example embodiment 8 wherein said carrier gas comprises less than about 10 percent by volume of diatomic oxygen.

15. The process of example embodiment 1 wherein the concentration of CO₂ in the gas comprising CO₂ is greater than about 95 volume percent.

16. The process of example embodiment 1 wherein the partial pressure of CO₂ in the gas comprising CO₂ is greater than about 1.5 atm.

17. The process of example embodiment 1 wherein the calcining of calcium sulfite to calcium oxide, or the calcining of magnesium sulfite to magnesium oxide, or both further comprises forming a gas comprising sulfur dioxide.

18. The process of example embodiment 16 further comprising absorbing at least a portion of said gas comprising sulfur dioxide into a solution comprising water to form aqueous sulfur dioxide.

19. The process of example embodiment 17 wherein at least a portion of said solution comprising water comprises the permeate comprising water.

20. The process of example embodiment 1 further comprising employing an ant-scaling chemical.

21. The process of example embodiment 1 which further comprises heating a remaining solution after precipitating magnesium sulfite mixed said remaining solution with said aqueous magnesium sulfite before or during concentrating by the membrane based process. 22. The process of example embodiment 1 which further comprises removing at least a portion of non-magnesium sulfite impurities from a remaining solution after precipitating magnesium sulfite. 23. The process of example embodiment 22 which further comprises heating and mixing the solution with at least a portion of impurities removed with the aqueous magnesium sulfite before or during concentrating by the membrane based process. 24. The process of example embodiment 1 which further comprising employing a remaining solution after precipitating magnesium sulfite to absorb at least a portion of any sulfur dioxide produced calcining of calcium sulfite or calcining of magnesium sulfite. 25. The process of example embodiment 1 which further comprises recovering at least a portion of any sulfur dioxide produced by calcining of calcium sulfite or calcining of magnesium sulfite by cryogenic separation. 26. The process of example embodiment 1 which further comprises distilling at least a portion of a remaining solution after precipitating magnesium sulfite. 27. A process for producing calcium oxide, magnesium oxide, or both from a material comprising calcium and magnesium comprising:

reacting a material comprising calcium and magnesium with sulfur dioxide to form a solid comprising calcium sulfite and magnesium sulfite;

contacting said solid comprising calcium sulfite and magnesium sulfite with water to form a liquid solution comprising aqueous magnesium sulfite; and

separating said solid comprising calcium sulfite from said liquid solution comprising aqueous magnesium sulfite.

28. The process of example embodiment 26 further comprising concentrating said aqueous magnesium sulfite using a membrane based process to form a concentrate solution comprising magnesium sulfite and a permeate comprising water.

29. The process of example embodiment 26 further comprising precipitating solid magnesium sulfite from said concentrate solution comprising aqueous magnesium sulfite.

30. The process of example embodiment 26 further comprising drying said precipitated solid magnesium sulfite using a carrier gas with a diatomic oxygen concentration of less than about 3 volume percent.

31. A process for producing magnesium oxide from a material comprising calcium and magnesium comprising:

reacting a material comprising calcium and magnesium with a solution comprising aqueous sulfur dioxide to form a liquid solution comprising aqueous magnesium sulfite, and a solid comprising calcium sulfite;

separating said solid comprising calcium sulfite from said liquid solution comprising aqueous magnesium sulfite;

concentrating said aqueous magnesium sulfite using a membrane-based process to form a concentrate solution comprising magnesium sulfite;

precipitating solid magnesium sulfite from said concentrate solution comprising aqueous magnesium sulfite; and

calcining said solid magnesium sulfite to produce magnesium oxide.

Example Embodiments Citric Acid Production with Bisulfite Intermediate

1. A process for producing an alkaline-earth oxide and a carboxylic acid from an alkaline earth cation-carboxylic acid anion salt wherein the process comprises:

reacting an alkaline-earth cation-carboxylic acid anion salt with aqueous sulfur dioxide to produce aqueous alkaline-earth-bisulfite and aqueous carboxylic acid solution;

desorbing sulfur dioxide from said aqueous alkaline-earth-bisulfite and aqueous carboxylic acid solution to produce alkaline-earth-sulfite solid and aqueous carboxylic acid solution;

separating said alkaline-earth-sulfite solid from said aqueous carboxylic acid solution; and

calcining said alkaline-earth-sulfite solid to produce alkaline-earth-oxide, cement, or a combination thereof.

2. The process of example embodiment 1 wherein said alkaline-earth cation comprises calcium cation.

3. The process of example embodiment 1 wherein said alkaline-earth cation comprises magnesium cation.

4. The process of example embodiment 1 wherein said carboxylic acid anion salt comprises citric acid anion salt.

5. The process of example embodiment 1 which further comprises separating aqueous carboxylic acid solution into isolated carboxylic acid and water.

6. The process of example embodiment 5 which further comprises absorbing sulfur dioxide with said water to generate aqueous sulfur dioxide for the reacting step.

7. The process of example embodiment 1 which further comprises absorbing said desorbed sulfur dioxide in water to produce aqueous sulfur dioxide.

8. The process of example embodiment 1 wherein said calcining said alkaline-earth-sulfite solid produces sulfur dioxide.

9. The process of example embodiment 8 which further comprises absorbing said sulfur dioxide in water to produce aqueous sulfur dioxide.

10. The process of example embodiment 1 which further comprises reacting said alkaline-earth-oxide with water to produce alkaline-earth-hydroxide.

11. The process of example embodiment 10 wherein said reacting produces heat and wherein said heat is used in the process.

12. The process of example embodiment 10 which further comprises reacting said alkaline-earth-hydroxide with a solution comprising a carboxylic acid to form alkaline-earth cation-carboxylic acid anion salt.

13. The process of example embodiment 12 wherein at least a portion of said alkaline-earth cation-carboxylic acid anion salt is a solid.

14. The process of example embodiment 13 which further comprises separating said alkaline-earth cation-carboxylic acid anion salt using solid-liquid separation.

15. The process of example embodiment 1 wherein said separating comprises a solid-liquid separation step.

16. The process of example embodiment 1 wherein the process is conducted in the presence of a low diatomic oxygen environment.

17. The process of example embodiment 1 wherein said calcining is conducted under conditions to substantially prevent the formation of sulfate.

18. The process of example embodiment 1 which further comprises producing a precipitated alkaline-earth-carbonate from said alkaline-earth-hydroxide.

19. The process of example embodiment 18 wherein said precipitated alkaline-earth-carbonate comprises calcium carbonate, magnesium carbonate, or both.

20. The process of example embodiment 10 wherein said alkaline-earth-hydroxide is dissolved in water.

21. The process of example embodiment 12 wherein said alkaline-earth-hydroxide is dissolved in water.

22. The process of example embodiment 12 wherein said alkaline-earth-hydroxide comprises calcium hydroxide.

23. The process of example embodiment 5 wherein said isolated water comprises dissolved sulfur dioxide.

24. The process of example embodiment 22 which further comprises separating sulfur dioxide from the isolated water.

25. The process of example embodiment 10 wherein said reacting produces heat and wherein said heat is used desorb sulfur dioxide, separate water, or both.

26. A process for producing calcium oxide and carboxylic acid from a calcium cation-carboxylic acid anion salt wherein the process comprises:

reacting a calcium cation-carboxylic acid anion salt with aqueous sulfur dioxide to produce aqueous calcium bisulfite and aqueous carboxylic acid;

desorbing sulfur dioxide from said aqueous calcium bisulfite and aqueous carboxylic acid solution to produce calcium sulfite solid and aqueous carboxylic acid solution;

separating said calcium sulfite solid from said aqueous carboxylic acid solution; and calcining said calcium sulfite solid to produce calcium oxide, cement, or a combination thereof.

27. A process for producing calcium oxide and citric acid from calcium citrate wherein the process comprises:

reacting calcium citrate with aqueous sulfur dioxide to produce aqueous calcium bisulfite and aqueous citric acid;

desorbing sulfur dioxide from said aqueous calcium bisulfite and aqueous citric acid solution to produce calcium sulfite solid and aqueous citric acid solution;

separating said calcium sulfite solid from said aqueous citric acid solution; and

calcining said calcium sulfite solid to produce calcium oxide, cement, or a combination thereof. 

What is claimed is:
 1. A process for producing calcium oxide and citric acid from a calcium cation-citrate anion salt wherein the process comprises: reacting a calcium cation-citrate anion salt with aqueous sulfur dioxide to produce solid calcium sulfite and an aqueous citric acid solution; separating said calcium sulfite solid from said aqueous citric acid solution; and calcining said calcium sulfite solid to produce calcium oxide, cement, or a combination thereof.
 2. The process of claim 1 wherein said calcining calcium sulfite solid produces sulfur dioxide.
 3. The process of claim 2 which further comprises absorbing said sulfur dioxide in water to produce aqueous sulfur dioxide.
 4. The process of claim 1 which further comprises desorbing residual aqueous sulfur dioxide from the aqueous citric acid solution.
 5. The process of claim 1 which further comprises separating aqueous citric acid solution into separated citric acid and water.
 6. The process of claim 5 which further comprises absorbing sulfur dioxide with said water to generate aqueous sulfur dioxide for the reacting step.
 7. The process of claim 5 wherein said separated water comprises dissolved sulfur dioxide.
 8. The process of claim 1 which further comprises reacting said calcium oxide with water to produce calcium hydroxide.
 9. The process of claim 8 which further comprises reacting the calcium hydroxide with a gas comprising carbon dioxide to produce calcium carbonate.
 10. The process of claim 9 wherein said gas comprises air, or a flue gas, or an emissions gas, a biogas, or a natural gas, or a fermentation gas, or any combination thereof.
 11. The process of claim 8 which further comprises reacting the calcium hydroxide with a carbonate or bicarbonate salt.
 12. The process of claim 11 wherein said carbonate or bicarbonate salt comprises an alkali metal cation-carbonate or bicarbonate salt.
 13. The process of claim 11 wherein said carbonate or bicarbonate salt comprises an aqueous solution comprising sodium carbonate, or potassium carbonate, or sodium bicarbonate, or potassium bicarbonate, or any combination thereof.
 14. The process of claim 8 wherein said calcium hydroxide is dissolved in water.
 15. The process of claim 8 wherein said calcium hydroxide comprises a solid suspended in water.
 16. The process of claim 8 wherein said reacting produces heat and wherein said heat is used to desorb sulfur dioxide, or separate citric acid, or separate water, or dry calcium sulfite, or any combination thereof.
 17. The process of claim 8 wherein said reacting produces heat and wherein said heat is used in the process.
 18. The process of claim 8 which further comprises reacting said calcium hydroxide with a solution comprising citric acid to form calcium citrate.
 19. The process of claim 18 wherein said solution comprising citric acid comprises a fermentation broth, or a microbial solution, or a fruit juice, or a submerged fermentation solution, or any combination thereof.
 20. The process of claim 18 wherein at least a portion of said calcium citrate is a solid.
 21. The process of claim 20 further comprises separating said calcium citrate using a solid-liquid separation step.
 22. The process of claim 1 wherein said separating comprises a solid-liquid separation step.
 23. The process of claim 1 wherein the process is conducted in the presence of a low diatomic oxygen environment.
 24. The process of claim 1 wherein said calcining is conducted under conditions to prevent the formation of sulfate. 